US2171587A

US2171587A - Instrument for making perspective drawings from plan and elevation

Info

Publication number: US2171587A
Application number: US149901A
Authority: US
Inventors: Donald T Mcgregor
Original assignee: Individual
Current assignee: Individual
Priority date: 1937-06-23
Filing date: 1937-06-23
Publication date: 1939-09-05
Anticipated expiration: 1956-09-05

Description

Sept. 5, 1939. D. T. MCGREGOR INSTRUMENT FOR MAKING PERSPECTIVE DRAWINGS FROM PLAN AND ELEVATION l ild June 23, 1957 3 Sheets-Sheet l regor HZ iorneys.

Inventor. D. T. Ala-6' Sept. 5, 1939. D. Ti'McGREGoR 2,171,587

INSTRUMENT FOR MAKING PERSPECTIVE DRAWINGS FROM PLAN AND ELEVATION Filed June 23, 1957 Sheets-Sheet 2 251 304 2 115 110 26.5 05 203 124 2 u. u u .LZ 31 32 a 8 @II 201 I F F 228 333 121 222 226 vlllll 124 (4i I'.I r Z5 18 I 125 15 128 129 123 Fr .6. 237 q 11 Invenfor.

D. T. McG'z'egor Sept. 5, 1939. D. T. McGREGOR INSTRUMENT FOR MAKING PERSPECTIVE DRAWINGS FROM PLAN AND ELEVATION A m mw 3 mm$ W M R 1% W m mwv w w w r e S G W D aw .wmw .wmw x NE e c r e n a WM Patented Sept. 5, 1939 UNH'E. STATES PATENT OFFICE INSTRUMENT FOR MAKING PERSPECTIVE DRAWINGS FROM PLAN AND ELEVATION Claims.

My invention relates to a drawing instrument for use on a relatively large drawing board or drawing table to make approximately true perspective drawings taken directly from a plan 5 and an elevation of the structure to be shown in perspective, the plan and the elevation manifestly being on the same scale. Therefore with my instrument by mounting on a drafting table an elevation of a structure and at another position mounting a plan at the desired angle to the edge of the paper to show the desired perspective, then'on another part of the board a perspective may be traced or drawn by a pencil using an equipment of several pantographs to produce the lines of elevation and the outline of the plan.

A main object and feature of my invention resides in an instrument by which for instance a first pantograph assembly may have a guided portion located at elevation view at any desired heighth thereon. By means of a second pantograph assembly, a pointer is guided around the outline of a plan at the same elevation, then by the interconnection of the two pantograph assemblies, a third type of pantograph having a pencil thereon outlines the perspective of the plan at the particular heighth, hence by drawing plans at diiierent heighths of the elevation and also shifting the elevation pantograph system, the pencil will draw a perspective to close approximation and preferably on a slightly smaller scale than the scale of the original plan in elevation.

Another object and feature of my invention relates to interconnecting mechanisms between the three pantograph assemblies whereby pivotal points of such assemblies are changed in position and in which rectilinear motions are produced as to certain of these pivotal points along lines at right angles one to the other, for instance along a vertical and a horizontal line. My invention also comprehends features on which certain of the pivotal points of some of the pantograph assemblies move on radial lines in relation to a center and there is an interconnection between one pantograph and another to cause the positive sliding movement of various center points of the several pantograph systems.

A characteristic of my invention relates to the principle or procedure of making an approximate perspective drawing. In this operation a plan and elevation drawing for instance of a building are placed on the same plane surface such as a drawing table or large drawing board.

The elevation is located in the usual manner with for instance the ground line on a so-called horizontal line on the paper, the plan is then located in such a position on another part of the table so that the draftsman in visualizing the sides of the plan nearest him will have in mind drawing the perspective to show such sides. Theoretically the drawing is done by a series of projections. For instance in viewing the plan a station point is established either on the drawing table or the extension thereof, this being intended to indicate the location of the eye of the draftsman. Converging lines are then drawn from prominent portions of the plan such as the corners of a building to converge to the station point. Intermediate between the station point and the plan is established a picture plane. This may be indicated on the drawings as a line parallel to a horizon line and the converging lines intersect such a picture plane. 20 Such points of intersection are then projected downwardly towards the picture point but at right angles to the picture plane and thus will define vertical lines of the elevation such as corners of a building but does not determine their length.

To define the length of such lines, for each vertical line on the plan, as for instance a prominent corner of a building, a second station point is established on the drawing table and a sec- 30 0nd picture plane, this being relative to the ele' vational drawing only. Converging lines for instance from the bottom and the top of a particular corner line are drawn to the second station point and intersect the second picture plane. Then horizontal lines are projected from this second picture plane, that is, from the points of intersection and parallel from the horizon line to intersect the particular projection from the plan of the same elevation line or corner and thus define the length of such corner on a perspective plan. Similar projections can be made taking different station points for each prominent vertical line of the plan and thus deter mine the length of the projections from the plan to form the perspective. Then by means of a drafting instrument the various intersecting points may be connected and outline the perspective.

If the plan drawing should be different for difierent heighths on the elevation, different plans will be substituted to define the perspective outline of a particular plan with the different heighths of the elevation drawing. Of course it is manifest that the plan and the elevation should be drawn on the same scale.

A main characteristic and object of my in vention is hence by a mechanical instrument by a method of procedure to make the equivalent of the above projections defined in relation to the principle of the invention to draw in the approximate perspective drawing without making the detail actual projections. Hence for this purpose I employ a base or supporting structure Which may be placed on the drafting table and I utilize a first pantograph system preferably with a straight edge indicating device to align with any particular heighth on the elevation drawing, the first pantograph having arms pivoted to the base and mounted to sweep over the elevational drawing. This first pantograph system is connected to operate a first sliding frame having a so-called vertical movement over the supporting base.

A second pantograph system has a tracing pointer and is provided with one pivot in a fixed position on the base and a second movable pivot which in operation of the tracing pointer over a plan outlines in miniature the shape of the plan or any particular line on the plan. My invention also has as an important feature the interconnecting of the first frame and this moving pivot of the second pantograph system. To effect this connection a lever is slidably and pivotally mounted on the base, the pivot also being adjustable. This lever has a pivot to the second sliding frame and also has a double swivel slidable thereon which also slides on a guide parallel to a horizon line. The pivot of the second pantograph system is slidably mounted on a second lever which also has a sliding and pivotal connection to the base and a pivotal connection to a second frame slidable on the horizontal guide on the base. In addition the pivot of the second pantograph system and the double swivel on the first frame are interconnected for joint movement. The first lever has a pivotal connection to a third frame which also slides on a guide in a vertical direction. Therefore to operate a pencil or the like for drawing. the perspectve, a third pantogra-ph system has pivotal connections to the second and. to this third sliding frame.

Another feature of my invention relates to an interconnection between the first and second pantograph systems particularly adapted for drawing on the perspective outlines in the elevation in one vertical plane. For this purpose the straight edge of the first pantograph system is provided with a movable pointer, movable along horizontal lines on the elevation and the tracing pointer of the second pantograph system is provided with a straight line guide which is placed on a plan in alignment with the particular side having the elevation to be traced. The pointer of the second pantograph system is interconnected with the pointer on the first system so that when the pointer moving over the elevation follows a particular outline, the pointer of the second pantograph is forced into a straight line movement. These two" actions develop a movement of the pencil on the third pantograph system to trace the particularoutline on the per-.

spective drawing and in substantially a correct perspective. Various other features of importance'are embodied in my invention which are described in the detail description of the instrument and the manner of operation.

My invention is illustrated in connection with the accompanying drawings, in which:

Fig. 1 is a plan of my instrument showing the relationship of the various pantograph assemblies to an elevation drawing, a plan drawing on the same scale and the perspective being executed by the pencil. For the sake of clarity certain pivot points are shown oifset from their preferred position, the instrument developing however an approximate perspective. 7

Fig. 2 is a vertical section on the line 22 of Fig. 1 in the direction of the arrows showing the mounting of the straight line or tensioned wire to be set at various heighths on the elevation drawing.

Fig. 3 is a detail vertical section on the line 3-3 of Fig. 2 showing the mounting of the guide pointer operating over the plan and a small wheel to support the pointer out of contact with the paper.

Fig. 4 is a vertical longitudinal section on the line -L of Fig. 1 in the direction of the arrows showing details of a pivotally mounted arm and a sliding support for one of the pivots of the pantograph connected to the tracing pointer.

Fig. 5 is a vertical longitudinal section on the line 55 of Fig. l in the direction of the arrows showing details of another pivoted arm and the connection of a sliding pivot.

Fig. 6 a vertical section on the line 6-6 of Fig. l in the direction of the arrows showing the mounting of a sliding vertical cross arm operating on a horizontal guide.

Fig. 7 is a vertical transverse section on the line ll of Fig. 1 in the direction of the arrows showing in cross section a main guide rod and a block slidable thereon having one of the pivots for the pant-ograph assembly leading to the pencil.

Fig. 8 is a vertical section on the line 8-8 of Fig. 1 showing a pivoting guide for an angularly moving and slidable rod or arm.

Fig. 9 is a vertical section through one of the pivots and may be considered on the section line 9-4! of Fig. l in the direction of the arrows.

, Fig. 10 is a plan showing part of the pantograph systems for the elevation and plan with appiiances atached thereto for outlining on the perspective structures in the same vertical plane, that it, in which a pointer follows the elevation instead of a pointer following the plan. With this equipment the pointer for outlining a plan is forced to travel in a straight line.

' Fig. 11 is a detail vertical section on the line i l-l I of Fig. 10 in the direction of the arrows.

Fig. 12 is a vertical detail section on the line i 2l2 of Fig. 10 in the direction of the arrows.

Referring to the principal drawing which is l, a substantial and rather heavy base plate 5? is utilized. This is defined by the bottom edge it, a lower left hand corner edge I 3, a left hand side edge i i, an inclined left hand upper side edge i5, 2. right hand edge 56 and a lower right hand edge ll. These various edges merge with curved corners which are of short or radius but they may meet at angular corners if desired. The base plate is supported on the drafting table by a series of prongs l8. Thus the plate itself is elevated above the drafting table.

In view of the usual terminology in drawings in which the paper is presumed to occupy a vertical plane and feather, in view of the plan of operation of the device, it is necessary to refer to so-called picture planes and horizontal lines, certain of the elements of construction are designated as being vertical and the other as horizon tal. Thus there is a vertical guide structure 29 which utilizes a pair of end studs 2| and 22 with a cylindrical rod 23 clamped to these studs and thus spaced above the base plate I I. This rod is thus defined as forming a horizontal guide or track on which certain moving parts hereinunder described operate. There is a horizontal. guide 25 which also employs

end studs

26 and 21 supporting a horizontal rod 28, this also being shown as cylindrical and is thus supported above the base plate ll.

The first pantograph system or assembly desig nated by the numeral 39 may be defined as the elevational pantograph. This employs two parallel arms 34 pivoted to the base II at 32 and the arm 33 pivoted to the base II at 34. These are connected by a horizontal arm 35 by connecting pivots 3t and 3? and from the same pivots there are two parallel arms 33 and 39. These are pivoted to a straight edge assembly it, note the details in Fig. 2, which straight edge employs a horizontal bar @2, angle straps 43, with a vertical section 44 and a horizontal section 45. The pivots ii -3 and il of the arms 38 and 39 being connected to the horizontal section, these pivots are directly over a straight edge wire 48 which is stretched between the two parallel vertical ends 9 and 5!] of the bar @2. The wire may be tightened by a screw arrangement 5!. This wire should be quite fine in order not to obstruct details shown in the elevation. Aline through the

pivots

32 and 36 is parallel to the straight edge wire 43 and this wire is presumed to occupy a horizontal line in reference to an elevation of a structure for which a perspective drawing is to be made.

The p-antograph assembly so far described em- I ploys a secondary pantograph system designated A lug 82' bar 95 which has an arm 56 forming a continuation of the arm 3?), these preferably being formed integral. A side arm 5'? is connected by a pivot 58 to the end of the combined arm 39 and 56 and an arm 59 parallel to the arm 56 connects from the pivot 3 on the base II to a pivot 55 on the arm 57.

A sliding i'rame I5 is mounted on the guide rod or track 23. This has end hubs l6 and El, each with perforations through which extends the rod 23. Sides i8 and it converge from these hubs to the outer end 86 which is illustrated as curved, a base 3i connects the hubs and between the base and the apex there is a horizontal guide 82. Thus the frame 35 may be considered as of triangular shape. It is shown as having an open center between the sides 58 and l9 and the center guide for sake of convenience in construction. is formed integral with the side 12 and a main pivot 83 secures the arm Bl to this frame it, such arm having an extension 84. It will be seen that this main pivot 83 is always at a fixed distance from the vertical guide rod 23 and hence in any movement of the straight line edge assembly :36 which is always parallel to the horizontal, develops a vertical movement of the frame If; on the guide rod '23, the medium for moving this frame being by the arm 51 having its extension fi l. When it is desired to position the straight edge Wire 38 in alignment with a specific heighth on an elevation drawing, the pantograph assembly 3% may be clamped. This employs a clamping device 98 having a slotted ivoted at 92 to the extension 54 of the arm 5i and having a clamp set screw 93 threaded into the arm 59. Thus when this set screw is tightened the pantograp-h assembly 36 is immovable and the frame I5 is held in a fixed position.

The second pantograph assembly I93 which may be defined as the plan tracing pantograph employs a main arm IllI connected to the base II by a main pivot I02. A tracing arm I83 has a pivot connection Iil i to the end of the arm IIlI. An arm B85 parallel to the arm I! has a pivot IE6 to the arm I03. A short arm I81 parallel to the arm Hi3 has a pivot I08 to the arm I39 and a sliding pivot assembly I II].

This sliding pivot assembly (note particularly Fig. 4) has a guide block III with preferably a rectangular slot H2 therethrough, a pivot screw E1! has a bushing 5M and extends through eyes in the ends of the arms I65 and H11.

A substantial radius arm assembly I is preferably made of a guide rod I2! rectangular in cross section and having a drop portion I22 and a swivelling pivoted lower portion I23. This passes through a guide I24 which guide is formed of a lower plate I25 and an upper plate I25 secured together by screws IN. This forms an assembly fastened by a pivot screw I28 to the base HI adjacent the lower edge I2, the base having a recess I29 and a bushing I surrounding the pivot screw. It will thus be seen that when the arm IE3 is given an arcuate movement more or less in a horizontal direction. that is, to a certain extent parallel to the guide 28. that the pivot assembly i It moves in an arc. This causes the arm I22 with its sliding portion I23 to also move on an arc and to have a slight sliding motion through the pivot guide I24, this guide turning on the pivot screw I28. If the end of the arm $3 is moved in a more or less vertical direction, that is, to a certain extent parallel to the guidetrack 23, the pivot assembly Il slides on the guide rod till. The pantograph assembly I90 is manipulated by a tracing device I (note Fig. 3). This employs a long bushing MI fixedly secured in a perforation I42 on the end of the arm I03. A threaded bolt I43 extends upwardly through the bushing and at its lower end has a head I44 with a pointer M5. This is flattened on opposite sides and has a fine indicating point I46. A roller IA! is journalled on a stub shaft I48 extending through the pointer so that the periphery of the wheel rolls on the paper over a plan, the tip end of the pointer being closely contiguous to the paper without a contact therewith. A thumb nut I49 threaded on the upper end of the bolt clamps suificiently tight on the upper portion of the bushing to hold the pointer in place but to allow swivelling.

A vertically slidable frame designated by the assembly numeral I60 is interconnected for sliding movement by the action of the pantograph assembly Bil when the line wire 48 is moved to difierent heighths on the elevation drawing. This employs a block IS! with a longitudinal perforation I62 therethrough through which passes the vertical guide rod 23, such block may thus travel longitudinally of this block. An offset lug I63 has a main pivot screw connection I54 to a radial guide lever assembly I16. This employs a rectangular lever rod structure I]! (note particularly Figs. 1, 5 and 8). This is preferably a straight rod and operates through a swivel guide I32. This may be constructed substantially the same as the swivel guide I24 (note Figs. 1 and 4). Thus on account of the pivot I64 being confined to a vertical movement parallel to the guide rod 23, the horizontal or projected distance between the pivot ltd and the swivel screw I13 of the swivel guide H2 is always constant therefore there must be a slight sliding movement of the lever rod Ill through the guide I72.

The oscillating movement of the lever rod assembly H6 having the rod III is through the medium of double swivel guides I80 (note particularly Figs. 1 and 5). This employs a guide block 585 with an opening which extends the lever rod I1 I. An upper swivel block l 85 is preferably formed of a lower block secion tilt with a groove therein and an upper clamping block I'B'l. This forms a guide for the horizontal guide 82 which as above mentioned, is a fixed horizontal guide in the sliding frame 15. The lower block I8I and the upper block 85 are connected by a swivel screw 538, this being located in a socket I89 in the lower part I 86 of the upper block, the screw being threaded into the lower block till but this screw does not contact the lever rod I! I. By this construction when the pantograph assembly 39 moves shifting. the horizontal line wire 48 up and down over the elevational drawing, the frame I5 slides vertically on the guide rod 23 and from the motion transmitted through the guide block I85, the pivot screw l 88 to the lower guide block I8! an arcuate movement is communicated to the lever rod Ill.

The swivel guide In is adjustable on the base Il, there being a series of horizon line perforations I95 (note particularly Fig. 8), there being a socket or recess I95 below each perforation so that the pivot screw H3 may be fitted upwardly through the underside of the base I I and may be located in any one of the perforations. The particular regulation is defined hereunder.

A horizontally slidable frame 260 is shown particularly in Figs. 1 and 6 and is slidable on the horizontal guide rod 28. This employs a guide sleeve 29! preferably cylindrical at the end portions 2&2 and having either a rectangular or fiat sided sleeve hub 203. The rod 28 extends through this sleeve having a snug sliding fit. A stiff plate 2% is fastened. to the hub 233 by screws 2&5. This plate is at right angles to the guide rod 28 and is thus parallel to the vertical guiderod 23. An upper pivot 29% connects the plate 23 to the oscillating lever rod I2! and thus makes the relatively fixed pivot through which said rod oscillates. The vertical projected distance between this pivot 296 and the pivot pin 52% of the swivel guide I24 is thus always con-- stant while the frame assembly 2% slides on the horizontal guide rod 28, thus it is necessary for the lever rod 225 to have a slight sliding motion in the swivel guide I 24.

It is necessary to have an interconnection between the pantograph assembly 30 adjustable as to the different heighths on an elevation drawing and the pantograph assembly H16 in which the tracing device Mil follows the plan. Such interconnection is to correlate changes of the pivot points for tracing the drawing hereinunder detailed. Such interconnected assembly is designated by the numeral 226 (note Figs. 1, 4 and 5). This employs what might be considered as a Bowden wire assembly 22I, employs a wire 222 which as to its action is a contiguous wire operating through two

flexible guides

223 and 224. One end of the guide 223 is attached to the outer end of the lever rod I2! by a clamp 225 (note Fig. 4). The wire leads to the sliding pivot assembly Hi3, being illustrated as attached thereto by attaching

screws

226 and 22?. The wire extends thus longitudinally of the lever rod tilt and enters the flexible guide tube 224 which has one end secured to the lever Bill by a second clamp "228. The rod is illustrated as passing longitudinally on underside of the lever I 2|. The oppo- I82 therethrough through site end of the flexible guide 223 is attached to the horizontal guide 82 by a clamp 229, this being illustrated as connected to a block 230 riveted to the end of this guide etxending upwardly from the base 8i. A clamp 233 attaches a section 234 of the wire to the double swivel guide assembly iBil, being directly secured to the upper swivel block I35, this being by means of lower and upper clamping blocks 235 and 236, the block 235 being secured to the upper swivel block I85- and a screw 23? securely clamping the Wire. The section 234 of the wire extends parallel to the horizontal guide 32 andis illustrated as positioned above such guide and enters the end 238 of the guide 224 which is secured by a clamp 239 to the curved apex 83 of the sliding frame 75.

The interaction of the connection of the guide swivels ill} and I81] by the Bowden wire assembly is substantially as follows: Presuming the tracing or pointer guide its is held stationary, any up and down movement of the straight edge assembly it with its straight edge wire 48 does not cause any sliding movement of the swivel guide I88 or i it. However when the pantograph assembly 3% is held stationary bythe wire 48 being positioned at any desired heighth on an elevation drawing and the tracing device I 46 is moved in a more or less vertical direction, this action causes the swivel guide ME! to slide longitudinally on the lever rod I2I and manifestly on account of the continuous wire connection to the double swivel guide E80, this swivel guide is moved longitudinally, that is, considered horizontally, on the horizontal guide 82 and also the lower guide block lSi causes an arcuate move ment of the lever rod Ill.

The drawing pantograph assembly 253 employs a first arm 25! pivoted at its inner end at 252 to the horizontal sliding frame 263, this pivot being attached to the lower end of the plate 284 (note Fig. 6). The detail attachment employs a spacing block 253 attached by a short screw 254 to the plate 2%, the pivot screw 255 threaded into this block and passing through a bushing 255 an eye on the end of the arm 325i. However the manner of attachment is immaterial. A second arm 2% has its upper end secured by a pivot 25! to the vertically slidable frame I66, this being attached directly to the block iSI. The arms 25I and 2% are parallel and maintained parallel by an interconnecting arm 2% connected to the pivot 252, this having an eye through which the bushing 25:: extends (note Fig. 6). The other end of this arm is connected by a pivot 266 to the arm 28%. The pencil or drawing arm 215 has an innerpivot 2% connected to the outer end ofthe arm 266, a second pivot 2?! connected to the outer end of the arm 25L thus making the section 2'38 of this arm equal in length to the arm 255 and parallel thereto. A pencil holder 279 is secured to the outer end of the arm 2'55, this pencil holder extending downwardly and having a pointed lead pencil inserted at the lower end of the holder. Any suitable type of pencil holder may be used for this purpose. Considered in the general action, when the pantograph assembly Sii is set with the straight edge wire 48 at a desired heighth on an elevational drawing and the tracing assembly is moved over a plan, the pencil in the pencil holder 219 traces a perspective at such particular elevation.

The manner of operating and functioning of my invention may be considered substantially as follows: In the manner in which the instrument is set, a horizon line 280 is established and thus when the threaded edge wire 48 of the pantograph 35 is on such line it defines a heighth or elevation exactly in line with the horizon line. An elevation of a structure is indicated at 28L This is illustrated as having a front face 282, two end faces 283 and 284 and a pyramid type of roof 285 with an apex 285. The roof has ridged lines 28?. The plan is indicated at 2459 drawn to the same scale as the elevation in which 252 in dicates the front face, 283 and 28% the end faces, 29I the back or rear face, the roof is indicated with the apex 286 and the various ridge lines 281. The tracing pointer Me of Fig. 3 is illustrated as positioned at the corner of the sides and 283 and the straight edge line shown the elevation of the bottom of the roof.

If the straight edge wire is aligned with the horizon line 288 and on account of the structure being symmetrical, if the tracing point W3 is moved to follow the lines of the structure which may be readily done by using straight edges as a guide for the roller tell, the pencil 219 commences tracing the perspective drawing indicated at 300 making the horizontal and horizon line 3!, this being a straight line across the paper. The pantograph 32 may then be manip-- ulated to align the wire at with the base of the roof and then when the tracing device Us is moved around the lines indicating the plan, a tracing 30.2 is made, this being in perspective and shows a horizontal line see forming the upper edge of the front 282, a line 39% forming the upper edge of the side 283 and if desired, the rear edges which would not be visible in the perspective drawing may also be sketched in. For a simple drawing as shown by the plan in elevation, the apex 286 may be established by raising the wire .8 to the apex of the elevation and moving the tracing device Hill to bring the point to the apex of the roof as shown on the plan. This gives the apex point on. the perspective. The lines indicating the lower corners of the roof may then be joined with the apex by a straight edge. lhe vertical lines showing the corners of the structure may be located by the corners of the drawing 3252 and by locating similar points on the line 3%. These points may be connected by lines by a straight edge and thus make a perspective sketch which is approximately a true perspective.

The theory or proposition on which such a perspective is made is on the basis of considering a vertical picture plane on which it is presumed that a picture is to be made. This is located between the observer designated as imaginary station point and the plan and also the elevaticn drawings, there being however an imaginary picture plane for sketching the plan. and another picture plane for sketching the elevation distances, these changing for each vertical section or position of the elevation drawings. Thus for instance a miniature picture plane may be conside-red on the dotted line 3E9 (note Fig. 1). This passes through the pivot 2&5 on the sliding frame 2% and is thus parallel to the guide rod 28. A miniature imaginary station point is then at the pivotal center of the swivel guide 5 forming one of the pivots for the lever rod Hit. The line of picture plane for making the actual drawing on a larger scale than the miniature picture plane till is indicated by the dotted line 365, this being a horizontal line in the drawing. The imaginary station point is oii the field oi the drawing but the dotted lines 353, 3i? and 352 and other lines from distinctive points on the plan converge to this imaginary station point. These lines are illustrated as intersecting the line of the picture plane 3I5 at 3I9, 329 and 32! respectively. From these there are projections downwardly by the

lines

322, 323 and 324 which define lines or points of the plan 290 in the perspective drawing 380. The corner between the

sides

282 and 284 is in the projected line 322, the corner be tween the sides 283 and the back 29I is in the line 324 and the apex 285 of the roof is in the projected line 323.

Considering the reduced picture plane for the vertical, this may be considered as on the vertical dotted line 340 which line passes through the pivot I54. of the lever rod Ill and is parallel to the guide rod 23. This is illustrated as spaced slightly from such guide rod although it would be preferable to have such pivot directly in line with this rod. For making the perspective drawing 3% for instance to obtain the vertical line of the corner between the

sides

282 and 283, there is an imaginary vertical picture plane indicated by the dotted lines 3M and an imaginary station point 342 is in a continuation of the horizon line 283. A converging line 343 is drawn from the upper end 344 of this corner of the structure to the point 342 and likewise there is a line drawn from the lower end 345 of the corner to the same point 342, however this letter line is in the horizon line 280. These lines intersect the picture plane at 345 and 341 respectively. A projection line 348 then defines the upper corner 349 and a projection from 34'! defines the lower corner 35!). Thus the line 35I between these two corners gives the vertical projection of the vertical line forming the corner between the

sides

282 and 283.

Other characteristics of the assembly reside in the tracing pointer through the pivot of the swivel guide H5 and the pivot I82 of the pantograph I always being in alignment as indicated by the line 360. As the tracing pointer is moved the swivel guide H0 is moved a proportionate amount but the pivot I02 is always fixed, therefore although this line 355 changes in position these three points are always in alignment. Different scale for the reduction of the perspective may be made by changing the proportions of the arms of the various pantograph. In the set up of my equipment I have approximated that the distance between the pivot 26% on the frame 206 and the pivot of the swivel guide I IE3 on the lever rod I2l is always equal in length to the distance between the pivot I64 and the pivot of the double swivel block I85. However this is not absolutely correct and to give a correct perspective the distance of a projected line 335 from the center of the swivel guide H to the imaginary miniature picture plane 3Ill should always be the same as the distance between the pivot lS l and the pivot of the double swivel I80. However as the lever arm I2I as a rule only moves through a small arc, my arrangement approximates this correct distance. In making all of these various projections, the two projections as from the plan and the elevation are made by the pantograph assembly 256 with the pencil point. A characteristic of this pantograph is that the center line of the pencil holder 219, the pivot 252 on the moving frame 200 and the pivot 26! of the cam 25% on the moving frame IBI, are always in alignment, this being indicated for one position by the dotted line 310. Thus when the pantograph assembly 33 is stationary, with the straight edge wire 48 at any elevation and the tracer hill is moved on a plan, the pencil records the movement giving the lines their approximate perspective. It will be manifest that by changing the proportions of the pantograph systems that changes may be made in the relative scales of the original drawings, that is, the elevation in plan and the perspective.

In Figs. 10, 11 and 12, I illustrate attachments for the pantograph system 30 and the tracer system I09, this being to follow and develop an outline in elevation and in a vertical plane. The purpose of this is therefore to provide a pointer which is guided on the elevation over the portion to be shown in perspective and as the tracer end of the pantograph system operating over the plan moves in a straight line, this is confined to a straight line without the operator requiring to move two pointers at the same time.

The elevational tracer equipment is designated generally by the assembly numeral 400. In this and in the pantograph system 30 the straight edge assembly 40 with the straight edge wire 48 are removed and a movable elevational pointer assembly 40I is substituted. This employs a frame bar 402 (note particularly Fig. 11) with brackets 403 connected to the end pivots 46 and 47 of the arms 38 and 39. Right angular forwardly extending ends 404 and 4&5 form the support for a guide rail 406, this being shown as rectangular in cross section. A slidable guide block 401 has an opening therethrough and slides on this bar having an operating handle 498. A pointer arm 409 is secured to guide block 401 and has a tapered pointer end 4I0 with a downwardly projecting prong M I, this prong being adapted for guidance on the particular elevation to be traced by the pencil and such prong is in a direct line between the pivots 46 and 41. A pulley M2 is mounted on one end of the rail 406 and connected to the other end of the rail there is a clamp 4I3 securing the flexible sleeves or conduits 4 I4 and M 5 of a Bowden wire assembly 4I6. One of the stretches of wire 4II extends along the rail 406 from end to end and above such rail passing around the pulley 4I2. A return run M8 is connected to attaching screws M9 to the guide block 407.

The plan guide equipment designated by the assembly numeral 430 employs a relatively heavy elongated straight edge bar 43!, this having a straight line guide edge 432 with a slight bevel 433 thereabove. At each end there are end supports 434 for a longitudinally extending guide rail 435 (note particularly Fig. 12), this being illustrated as rectangular in cross section. A slide block 436 has an opening therethrough and slides on this rail. A pointer pin 43'! preferably extending through a perforation in the guide block. This has a pointed end 438 and a shoulder structure 439. The arm I03 has the long bushing I M left intact so that the pointer pin 43'! may be inserted upwardly through this bushing and attached by the thumb nut I49. Thus the construction of Fig. 12 may bereadily substituted for that of Fig. 3. The axis of the pointer pin has been designated as a pivot MI.

The Bowden wire assembly is attached at one end to the guide rail 435 by clamps 442 similar to clamps 4I3. One run of the wire outside of the conduit indicated at 443 extends longitudinally along and above the rail 435 and passes over an end pulley 444. The other run 445 is connected by terminal screws 446 to the block 436. It is preferable to employ two screws for attachment of the free ends of the wire in both of the

devices

400 and 430 as the proper tension may be thus develop-ed in the wire. From this construction, when the pointer M0 is moved longitudinally on its guides, it develops a reverse movement in the parallel strands of wire of the Bowden wire assembly and thus communicates a motion to the guide block 436 having the pivotal connection to the arm I03 and as the pivot 44I can only move in a straight line, this produces the action of the pantograph I00 when moved corresponding to a vertical face on a plan.

By the assembly of Figs. 10, 11 and 12 it will therefore be seen that the straight edge 43! may be positioned with its edge aligning with any straight line on a plan such as the line indicating a wall such as the wall or side 282 of the plan and elevation of Fig. 1, this straight edge being indicated in Fig. 10 in approximately such position. The pantograph assembly 30 may then be moved with the guide rail 4% always occupying various parallel positions and thus defining different heighths on the elevation. Hence by the draftsman combining the operation of the pantograph 30 as a whole with the movement of the pointer arm 4l0 With its prong 4 the outline of a structure or design on the elevational drawing may be as follows, this of course being in a vertical plane and as the pantograph system I00 is guided with its operating tracer point 439 moving in a straight line, the pencil on the arm 215 of the drawing pantograph assembly 250 will trace out the configuration or particular design on the perspective drawing.

It will be understood that in the use of my instrument the plan in elevation must be of such size that the pantograph system 30 for the elevation and Hit? for the plan can properly be moved over these. Of course it will be understood that where drawings of large'buildings or large scale drawings of plan in elevation are used, the instruments should be made to a proportionate scale. However in working on large plans or large scale plans the various pantograph systems may be proportionately enlarged. My instrument may also be used for developing in perspective a so-called birds-eye view of a building in which the base of the building would substantially coincide with the greatest spread that could be given to the pantograph system 30. Then the horizon line if the building is not too high, would be above the roof line. Then by using a plan of the roof the outline of this in perspective could be obtained and again by using a ground floor plan, this could be obtained in the perspective and the various corner lines connected.

My instrument in some cases, particularly in making plans of a low building, may be reversed. In such cases the elevation would be located in the space allotted to the plan. However, a horizontal line on such elevation should be vertical. Then the plan could be located'in a space usually occupied by the elevation and the wire 48 aligned for instance with the front face of a building. Then the pantograph I00 could be operated to trace in perspective the details on such vertical face or outside wall. For any'insets such as deep windows or doorways, the pantograph 30 would be adjusted accordingly and the pantograph IOIl used to trace in these details.

It will be noted that a feature of my invention in regard to the second pantograph system used for tracing the outline on a plan is that the sliding pivot IIO forms the same outline as is traced by the tracing pointer only on a smaller scale. Therefore as the first pantograph system for aligning on the elevation and a third pantograph system having the drawing parallel or the like being correlated to this sliding pivot H cause the pencil to form a similar outline only in an approximate perspective.

In the claims where I have used the term such as a horizontal guide and vertical guide and other similar expressions, these are in the sense as frequently used in connection with drawings in which lines in alignment to or parallel to the direction of vision of the draftsman are frequently spoken of as vertical lines and those at right angles thereto as horizontal lines. Also the so-called first or vertical guide is operative mainly in connection with the pantograph system operating over the elevation and the horizontal guide is operative mainly in connection with the second pantograph system operative over the plan or in a horizontal plane.

Various changes may be made in the details of the construction without departing from the spirit or scope of the invention as defined by the appended claims.

I claim:

1. In a device as described, the combination of a base structure, a first movable device having a series of pivotally connected arms with arm pivoted to the base at a fixed position, the said first device having means for aligning with an elevation drawing, a second outlining device having a series of interconnected arms with at least one arm pivoted to the base at a position thereon, the outlining means being adapted to follow the lines on a plan drawing, a third and tracing device having a series of interconnected arms with a tracing means on one of the arms, means forming an adjustable pivotal connection of the tracing means to the said base and an interconnection between the movable arms of the first and second devices to change the position of a pivot of the third device relative to the base.

2. In a device as described, a base structure with means for locating the same in fixed relationship to an elevation and a plan drawing on the same scale, a first pantograph system having aligning means adjustable over the elevation and having at least one pivot in a fixed position on the base, a second pantograph system having an outlining device to follow the outline of the plan, said second device having at least one pivot in a fixed relation to the base, a third pantograph system having a tracing means and having at least one pivot with an adjusting mounting relative to the base, means to interconnect additional pivots of the first and second pantographs to cause a relative change of position of the pivot of the third pantograph relative to the base.

3. In a device as described, the combination of a base structure having means for mounting on a drafting table in a fixed relation to an elevation and plan drawing, a first pantograph system having at least one pivot mounted in a fixed position on the base and having means for aligning with the elevation drawing and also having a second pivot adjustable as to the base, a second pantograph system having an outlining element to follow lines of the plan and having a third pivot mounted in a fixed position on a base and a fourth pivot adjustably mounted in relation to the base, a third pantograph system having a tracing element and fifth and sixth pivots with means adjustably connecting said pivots to the base and an interconnecting means between the second pivot of the first system and the fourth pivot of the second system and the two pivots of the third system to develop a movement of the tracing element in accordance with the position and movements of the aligning means of the first system and the outlining element of the second system.

4.111 a device as described and claimed in claim 3, the said inter-connecting means including a vertical and horizontal guide on the base structure, a block frame slidable on each guide and the fifth and sixth pivots of the third pantograph system being mounted on said sliding frames.

5. In a device as described, the combination i of a base structure having means for mounting on a drafting table in a fixed relation to an elevation and plan drawing, a first vertical guide and a second horizontal guide mounted on the base structure, a first frame slidably mounted on the first vertical guide, a second frame slidably mounted on the second horizontal guide, a first pantograph system having an elevation registering device adapted for operation over the elevation drawing and having at least a first pivot on the fixed structure and a second pivot on the first sliding frame, a second pantograph system having a tracing means for following an outline on a plan drawing and having a third pivot on the base structure and a fourth pivot having an operative connection to the second slidable frame, third pantograph system having a marking or drawing device and having a fifth pivot connected to a third slidable block frame mounted for sliding on the first vertical guide and having a sixth pivot connected to the second horizontally slidable frame and an interconnecting means between the fourth pivot of the second pantograph system and the third vertically slidable block frame and means to interconnect the first and third slidable frames, to correlate the movement of the three slidable frames on relative movement of the first and second pantograph systems and to operate the third pantograph system.

6. In a device as described and claimed in claim 5, the operative connection between the fourth pivot of the second pantograph system and the second frame including a first oscillating lever rod mounted on the base, said lever rod having a pivotal connection to the second frame and said fourth pivot of the second pantograph system having a slidable mounting on said first lever rod, a second lever rod pivotally mounted on the base and the third slidable frame, a swivel guide slidably mounted on the second lever rod and also slidably mounted in a rectilinear guide on the first frame to operate parallel to the second horizontal guide together with an interconnection between the fourth pivot of the second pantograph system slidable on the said first oscillating lever and the swivel guide slidably mounted on the second lever rod and the said rectilinear guide of the first slidable frame to thereby move the third frame.

'7. In a device as described, the combination of a base structure having means for mounting on a drafting table in a fixed relation to an elevation and plan drawing, a first vertical guide and a second horizontal guide mounted on the base structure, a first frame slidably mounted on the first vertical guide, a second frame slidably mounted on the second horizontal guide, a first pantograph system having an aligning edge for movement over an elevation drawing and having a first pi'vot connected to the base structure and a second pivot connected to the first slidable frame, a second pantograph system having an outlining device adapted to be moved over a plan drawing and having a third pivot on the base structure and a fourth pivot, a first oscillating lever rod slidably and pivotally connected to the base and pivoted to the second sliding frame, a first sliding assembly on said lever and having the fourth pivot of the second pantograph system connected thereto, a second oscillating lever rod pivotally and slidably mounted on the base and having a pivotal connection to a third slidable block frame mounted on the first vertical guide, said first sliding frame having a secondary straight line guide parallel to the second horizontal guide, a swivel block assembly slidably connected to the second lever rod and to the secondary guide of the first frame, means to interconnect the fourth pivot of the second pantograph system and the swivel block assembly to produce substantially equal movements as regards the movement of the respective pivots on the first lever and secondary guide of the first frame, a third pantograph system having a third marking or drawing device and having a fifth pivot connected to the second horizontal sliding frame and a sixth pivot connected to the third vertical sliding block frame.

8. In a device as described and claimed in claim 7, the lining edge structure of the first pantograph system having a movable pointer to follow an outline on an elevation, the outlining device of the second pantograph system having a pointer pin mounted thereon, such pin being supported in a slide block and said slide block being slidably mounted on a straight edge bar having an edge to align with a straight line on the plan drawing and means to interconnect the pointer and the said slide block to move the slide block in a straight line direction, and thus operate the second pantograph system to thereby operate the third pantograph system.

9. In a device as described, the combination of a base structure mounted on a drafting table having an elevation and a plan drawing fixed thereto, said drawings being in the same plane, a first frame sl-idably mounted on the base structure parallel to the drawings, a second frame slid- ,ably mounted on the base structure parallel to the drawings and at right angles to the direction of motion of the first frame, a third frame slidably mounted on, the base structure parallel to the drawings and to the motion of the first frame, a first lever having a pivotal and slidable connection on the base structure and having a nonsl'idable pivotal connection to the second frame, a third lever having a pivotal and slidable connection to the base structure and a non-slidable pivotal connection to the third frame, the first frame having a straight line guide parallel to the drawings and at right angles tothe direction of motion of the first frame, a sliding first pivot assembly slidably mounted on the first lever, a double swivel guide having a common pivot slidable on the second lever and also on the straight line guide of the first frame, means to interconnect the first sliding pivot on the first lever and a second double swivel guide whereby the distance of motion on the first lever between its pivot to the second frame and the sliding pivot and the distance between the pivot of the second lever to the third frame and the sliding double swivel remains substantially the same, a first device having an aligning means for movement over the elevation drawing and having an opera tive connection to the base structure and the first frame, a second device having means to trace an outline on the plan drawing and having a pivotal connection to the sliding pivot on the first lever and another connection to the base structure, a third device having a tracing or drawing element and having an operative connection to the second and to the third frame.

10. In adevice as described and claimed in claim 9, the said first device comprising a first pantograph system including an aligning edge device and two arms pivoted to the base and a third arm pivoted to the first frame, the second device including a second pantograph system including the tracing element and a first arm connected to the pivot on the first lever and a second elongated arm pivoted to the base, the third device including a third pantograph system with a first arm pivotally connected to the second frame and a second and longer arm pivotally connected to the third frame.

11. In a device as described and claimed in claim 9, the said first device comprising a first pantograph system including two arms pivoted to the base and a third arm pivoted to the first frame, the first pantograph having a straight line guide with a pointer slidably mounted thereon to follow an outline on an elevation drawing, the second device including a second pantograph system including a tracing pointer, a straight edge with a guide adapted to align with a straight line on the plan drawing, the second pantograph system including a first arm connected to the first pivot on the first lever and a second elongated arm pivoted to the base and means to interconnect the pointer of the first pantograph system and the tracing pointer of the second pantograph system to move said Winters an q distance on their guides.

12. In a device as. described, the combination of a base structure adapted for mounting on a plane surface drawing table to which may be aifixed an elevation and a plan drawing, a first movable frame adjustable on the base structure in a line parallel to a vertical line on an elevation drawing, said first frame having a guide structure positioned parallel to the plane of the table and parallel to a horizontal line on a plan drawing presuming an elevation drawing is positioned on thetable with horizontal lines parallel to the said guide of the first frame, a tracer element adapted to follow the outline of a plan and having a first main pivot, means to mount said pivot for a movement over the base structure whereby when the first frame is in a fixed position in accordance with a heighth on the elevation drawing and the tracer element outlines the plan at the same heighth, the said main pivot forms a similar outline of the plan in miniature, a tracing or drawing element, means interconnecting said element to the base structure and also having an interconnection to the first frame and to the first main pivot whereby the ferent heighth in the elevation may be made of the outline of the plan and in approximate perspective.

14. In combination with a drafting board having a plane drawing surface adapted to receive a plan and an elevation drawing, the elevation drawing defining horizontal and vertical lines combined with a base structure mounted on the board, a first adjustable device with means for aligning with an elevation drawing, a second adjustable device having means ior following the outline of a plan, the first device having at least one element pivoted to the base structure and at least another part having a combined sliding and pivoting connection to the base structure, the second adjustable device having at least one part pivoted to the base structure and a second part having a combined sliding and pivoting connection to the base structure, a third tracing device having a tracing pointer and having one element with means formingv a connection to the pivoting and sliding connection of the first device and having a second. element with a connecting means to the pivoting and sliding connection of the second device whereby on movement of the outline means of the second device the tracing means of the third device traces an outline on a drafting paper positioned in the same plane asthe plan and elevation drawings.

15. In combination with a drafting board having a plane drawing surface adapted to receive a plan and an elevation drawing, the elevation drawing defining horizontal and vertical lines combined with a. base structure with means to position same on the drafting board, the base structure having a main portion in a plane parallel to the plan and elevation drawings, a first vertical guide on the base structure, a second horizontal guide on the base structure, a first frame slidably mounted on the first guide, a second frame slidably mounted on the second and horizontal guide, a first elevation registering device having means for alignment on an elevation drawing and with a pivoted connection to the base structure and a second pivoted connection to the first sliding frame, a second tracing device having means to trace a line or outline on a plan drawing and having a first pivoted connection to the base structure and a second combined slidable and pivotal connection to the second sliding frame, a third marking device having means for drawing and an operative connection to both of said. frames, said operative connection comprising a block slidable on the first vertical guide and having a shiftable connection with the first movable frame, said third marking device having a second connection to the second frame sliding on the horizontal guide.

DONALD T. MCGREGOR.