US2538502A - Cursor - Google Patents

Description

Patented Jan. 16, 1951 v UNITED :S TATES- PATE NT F Fl C E onasoa .PauLEBoehm, Greenwich, Conn.

I Application October 16, 1947,'Serial'No. 780,132

1 iinverrtion relates to a slide rule :cursor. One of the objects or" invention .is .130 provide arslide rule inursorwhich is simple, practical and flIorough1-y durable Another object of this in- -vention lisito provide :a :device of the above char- :acter which facilitates reading and setting and thereby-enhances speed :and :accuracy of :slide mnleiwork. Another obiectioif EthiS invention is to rprovide ia xievice :01 the above character, the "use or which :Will reduce ceye :strain. :Still another (oliiectrofiinventioniis' to provide a deviceof the :above character, rt-he usefulness "of which is motafiedted byrscratch-ing and :dirt. -:Sti1l another rohiect (of tthis invention :is zto provide .a :device of the above character which :is :simple :in construcrtion and may the economically manufactured. .A .fiurther object of this invention is to provide 'a idervice :of above rcharacter :which facilitates :certaincalculationspnthe :slide rule by eliminating the necessity of income the slide iior 5110111211 operation. iOther objects will 'he in :part obvious sand in 'parit pointed 'out hereinafter.

invention accordinglyaconsists in the teaand arrangements of 'parts, all:as will 'he illustradiivly :describedrherem, and theiscopeof Liane-appliication which *will the indicated in the ?following claims.

:Referring :now to the accompanying drawing, in which :are ;s'howntwo of the various possible aemhodiments :of this invention,

:E'igure ;1 is .a perspective viewwof the cursor :mnun'ted son a :iportion of a slide rule; Figure 2 is :avertical tsection taken on the line 2-4 of Figure 11;

:E'igure 3:is .aiplan'of:a:modificationiof'the cursor :shown' in Figure :1 i mountedon a 'portion of a slide mule; and Figure'eis'a cuentical-sectionzofthe cursor taken on the line -;l'4 :of Figure B.

:Sim'ilar reference characters refer to similar parts throughout "the several views 'of the draw- 9mg.

conducive :to a clearer understanding :of :cerifeatures of :this invention, it might here be tnointed out vthat most :slide rules are equipped .atcursormade wholly pr in "part .of -'a "transparent material. portion of cursors now "in use'which is rpos'itionedabove the stock and slide zistusualiy aithinshee't or plate of transparent material-whichrhas a .hair line engraved or otherwise provided on the surface which faces and practically contacts "the graduated faces of the rs'hick and slide.

.JEt :hasbeen found thatthis :conventional 'type a cursor is :not .satis'factory tin rma'ny respects.

.6 .Claims. (Cl. 235-70) 'ttures of menstruation, combinations of elements,

In the :first place the production of a fine hair :line is a-delicate and rather costly manufacturing operation. .Another'difiiculty lies in the fact that in usesmall particles of dust, dirt, lint and the like accumulate in the minute space between the lower surface of the hair line plate of the cursor and the graduated faces of stock and slide. .These particles of foreign matter make it sometimes extremely hard to read thescale lines and numbers'and the little groove that makes-the hair line picks up dirt and dust so that the hair line becomes soonblurred and unsuitable for precise readings. .It is accordingly another Obie-ct of this invention to-overcome the above-mentioned difiiculties. 7

Referring now to the drawing; in Figures 1 and 2 a-sirnple slide rule. generally indicated at 9 with only one graduated face is shown. Slide rule 9 includes stock I!) and slide l. The cursongenerally indicatedat l2, covers'only the graduated faces ofstockfll andslide :H. Cursor i2 is made of one integral piece of transparent material including a main plate 13 with flange portions Id and -l 5 whichguide the cursor 12 along the stock 1 ll by means of the outside grooves It and H isthe stock with which the flange portions coact.

The plate I3 is provided with an opening or window 1.8 of rectangular shape. Window 18 has one .edge [9 .locatedapproximately in the center of the cursor l2 which extends at right angles to the direction ofmovement of cursor l2 and slide H along stock It. The margin 20 adjacent edgfe J9 is very thin and of substantial width. Margin I distortion and thus permit edge 19 to be correctly set to a numerical value between two adjacent raduation lines of the "scales oi the slide rule. If edge [9 'was'n'ot perpendicular, the distortion cau ed by'view'ing the scale through the edge I!) would cause the graduation line on the slide rule next tothe index edge but underneath margin 21! "to 's'eemto be nearer to the edge thanit really is.

Experiments have further shown that a cur- "sor with a window and index edge is far superior to 'a 'hairqine cursor. These portions of the scales that'are visible through the window it are seen directly and therefore in complete clarity because no cloudiness or discoloration of the cursor material obstructs the View: "No dust or foreign matter nor scratches can accuii-u1ate underneath .the cursor plate where clear visibility of :greatest importance.

color to make it appear a trifle darker or different from the color or shade of the face of the slide rule 9. This is of definite advantage to the users eye, as it accents line l9, making it much easier to align edge It with respect to a certain value on one or more of the scales, or to read the value corresponding to an actual position of the index edge It with respect to those scales, In contrast to this, when the conventional hair line is used, the eye is confused by the many graduation lines on both sides of the hair line. In using the cursor disclosed, the eye has to contend only with the graduation lines to one side of the index edge I9, namely, the lines visible in the Window I8.

It might here be pointed out that the description hereinabove is illustrative only, and that the invention is not limited to the features of the example illustrated and described above. It should also be pointed out that some cursors have more than one hair line, and accordingly the cursor described above may have more than one window or one or more windows with more than one index or index edge. As an example of such construction, referring to Figures 3 and a, the width of the window 18 may be made so as to equal the logarithmic value of 1r/4: on the A/B scale, and both lateral edges 2|, Zia of the window designed as index edges. Then, by setting the right-hand index edge 2| to X on the D scale, the area of a circle with diameter X may be read at the left index edge 2m on the A scale' Thus, a thoroughly efiicient and practical cursor has been disclosed which is efficient in use and economical to manufacture. It will thus be seen that the difficulties mentioned hereinabove have been successfully overcome and the objects successfully accomplished.

As many possible embodiments may be made of the mechanical features of this invention, and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinabove set forth'or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In a cursor for a slide rule or similar instrument, in combination, a plate member, means mounting said member on said instrument for movement longitudinally thereof, and means forming an opening in said member, said opening including at least one straight edge extendin transversely across the graduated surface of said instrument, the portion of said member adjacent said last-mentioned edge being transparent, relatively thin, and of a color different from that of the graduated surface of said instrument.

2. In a cursor for a slide rule or similar instrument, in combination, a plate member, means slidably mounting said member on said instrument for movement longitudinally thereof, the lower surface of said plate member being positioned a minute distance from the graduated surface of said instrument, and means forming an opening in said plate member, said opening having a pair of parallel edges positioned parallel with respect to the graduation lines on said instrument and serving as index edges with respect thereto, the portions adjacent said parallel edges being of substantially transparent material, said index edges being spaced from each other a distance which represents a predetermined numerical value at the logarithmic scale existing in at least one of the graduations of the Sl de ru iii 3. In a cursor for a slide rule or similar instrument, in combination, a plate member, means slidably mounting said member on said instrument for movement longitudinally thereof, the lower surface of said plate member being positioned a minute distance from the graduated surface of said instrument, and means forming an opening in said plate member, said opening having a pair of paralleledges positioned parallel with respect to the graduation lines on said instrument and serving as index edges with respect thereto, said index edges being spaced from each other a distance which represents a predetermined numerical value at the logarithmic scale existing in at least one of the graduations of the sliderule, the portions of said plate member adjacent said index edges being transparent and of substantially less thickness than said plate, and the faces of said edges lying in planes extending substantially at right angles to the graduated surface of said instrument.

4. In a cursor for a slide rule or similar instrument, in combination, a plate member, means slidably mounting said member on said instrument for movement longitudinally thereof, the lower surface of said plate member being positioned a minute distance from the graduated surface of said instrument, and means forming an opening in said plate member, said opening having a pair of parallel edges positioned parallel with respect to thegraduation lines on said instrument and serving as index edges with respect thereto, said index edges being spaced from each other a distance which represents a predetermined numerical value at the logarithmic scale existing in at least one of the graduations of the slide rule, the portions of said plate member adjacent said index edges being relatively thin, transparent, and of a shade or color different from that of the graduated surface of said instrument.

5. Ina slide rule construction of the tvpe wherein there is a stock which carries a central slide and which has a flange-receivingguideway at each edge, said stock and slide having faces in a common plane which carry graduation lines which extend transversely of the stock, a unitary cursor slideably mounted on said stock and including a plate portion positioned on said faces of the stock and slide and a pair of mounting portions extending along the respective edges of the stock and having flanges which ride in said guideways, said plate portion having an opening therein which xtends transversely of the said faces and which has a straight edge along one side which is a parallel to the said graduation lines on the stock and slide, said plate member having the portion forming said straight edgeformed of substantially transparent materialwhich is relatively thin and has parallel faces, said straight edge having its face in a plane extending substantially at right angles to the graduated surfaces of the stock. a

6. In a slide rule construction of the type wherein there is a stock which carries a central slide and which has a flange-receiving guideway at each edge, said stock and slide having faces in a common plane which carry graduation lines which extend transversely of the stock, a unitary cursor slideably mounted on said stock and including a plate portion positioned on said faces of the stock and slide and a pair of mounting portions extending along the respective edges of the stock and having flanges which ride in said guide-- ways, said plate portion having an opening therein which extends transversely of the said faces and which has parallel straight edges along the sides 7 2,538,502 5 i 6 which are parallel to the said graduation lines REFERENCES CITED on the stock and slide Said plate member having The following references are of record in the the portions forming said straight edges formed me of this patent: of substantially transparent material which portions are relatively thin and have parallel faces, 5 UNITED STATES PATENTS said straight edges having their faces in planes Number Name Date extending substantially at right angles to the 277,292 Knight May 8, 1883 graduated surfaces of the stock, said straight 460,930 Cox Oct. 6, 1891 edges being spaced from each other a distance 603,695 Keuifel May 10, 1898 which represents a predetermined numerical 10 747,098 Stanley Dec. 15, 1903 value in the logarithmic scale existing in at least 1,181,672 Keufiel May 2, 1916 one of said graduations. 2,387,404 Moyer Oct. 23, 1945 PAUL F. BOEHM. 2,392,877 Pym Jan. 15, 1946

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