US2837387A

US2837387A - Bases for operating tables

Info

Publication number: US2837387A
Application number: US441852A
Authority: US
Inventors: Greville Ernest Gordon
Original assignee: Individual
Current assignee: Individual
Priority date: 1954-07-07
Filing date: 1954-07-07
Publication date: 1958-06-03
Anticipated expiration: 1975-06-03

Description

June 3, 1958 E. G. GREVILLE BASES FOR OPERATING TABLES 4 Sheets-Sheet 1 Filed July '7 1954 June 3, 1958 E. G. GREVILLE 2,837,387

BASES FOR OPERATING TABLES Filed July 7, 1954 4 Sheets-Sheet 3 June 3, 1958 E. G. GREVILLE 2,837,387

BASES FOR OPERATING TABLES Filed July 7, 1954 /0 I III /4 4 Sheets-Sheet 4 This invention relates to bases for supporting equipment, such as operating tables, which is required to be mobile at times but is also required to be firmly set or rendered immobile at other times, and the invention is more particularly concerned with bases for such equipment having hydraulic means for regulating the height thereof above the floor.

A primary object of the invention is the provision of a base or carriage for equipment, such as an operating table, which base can be readily hydraulically converted from a condition in which it is mobile, on support means such as castors, to a condition in which it is relatively stabile, on support devices such as stump feet.

Another object of the invention is the provision of such hydraulically operable support means and devices in association with hydraulic equipment adapted to regulate the i height of the supported equipment above the floor.

A further object of the invention is the provision of control means for ensuring that the base, and thus the equipment carried thereon, is rendered immobile prior to the commencement of the elevational movement of the equipment and load.

Still further the invention has as an object the provision of control means whereby the unit (comprising a base and equipment carried thereby) can alternatively be rendered either mobile or stabile without altering the height adjustment and whereby the height can be increased or decreased without affecting the immobility of the unit.

Other objects and advantages of the invention will be more fully understood from the description of the invention referring to the accompanying drawings in which:

Figure 1 is a plan view of the base or carriage of the present invention;

Figure 2 is a side elevational view of the equipment 0 Figure 1, this view including a diagrammatic illustration of portions of an operating table in association with the equipment, this view illustrating the equipment in mobile condition;

Figure 3 is a plan view of a portion of the equipment shown in Figure 1, on an enlarged scale as compared with Figure 1, this view illustrating the pump, table lift ram and pressure release valve together with a portion of the pedal actuated mechanism for operating the pump and pressure release valve;

Figure 4 is a sectional elevation taken generally as indicated by the line 44 of Figure 3;

Figure 5 is a sectional elevational view of one of the stump feet of the invention taken generally along the line 5-5 of Figure l but on an enlarged scale as compared with Figure 1;

Figure 6 is a sectional elevational view of the relief valve of the invention taken generally along the line 6-6 of Figure 1;

Figure 7 is a sectional elevational view of the valve casing or junction box of the invention, this view being taken generally along the line 77 of Figure 8; and

Figure 8 is a plan view of the valve casing illustrated in section in Figure 7.

A 2337,38? Patented June 3, 1958 Hitherto mechanical means have been provided for immobilizing a table, for example, a lever, cam or screw has been adapted to raise the base olf its castors onto stump feet, or, alternatively, to lock the castor wheels.

According to the invention the base of an operating table, or like support, having castors, or the like, on which the base is mobile, and stump feet adapted to .render it immobile, is provided with hydraulic means for operating the stump feet, these means being preferably adapted to ensure that the stump feet are automatically adjusted to any unevenness of the floor.

When the base is applied to a table having hydraulic means for regulating the height of the table, such as a pump for supplying pressure fluid to alifting and lowering ram, the same pump may be used for supplying pressure fluid to the rams or plungers of the stump feet, but means are provided to ensure that when the pump is first actuated, the stump feet are first operated to immobilize the table, after which, on further operation of the pump, the pressure fluid is permitted to flow through a relief valve, balanced to the approximate weight of the table and patient, to the table ram to regulate its height.

Separate release valves are provided, one for the table lift ram and the other for the stump feet rams, so that the table base can be rendered mobile and immobile when required without interfering with the height adjustment of the table; or the height of the table may be adjusted without rendering the base mobile.

Turning to the drawings, especially Figures 1 and 2, a base B for an operating table T is provided with four castor wheels C. A hollow boss on the base adjacent to each castor encloses a hydraulic cylinder and is fitted with a ram or plunger having a lower enlarged cylindrical portion forming a stump foot SF (best shown in Figure 5) for engagement with the floor.

The stump foot cylinders are connected by separate pipes to a junction box or valve casing VC (best shown in Figure 7) which is fitted with separate ports and unions for the pipes. Each port is provided with a spring loaded ball check Valve. The union connections and valves are preferably arranged radially fromthe central part of the junction box in which pressure fluid, such as oil, is pumped through an inlet in the casing to which a supply pipe from a pump P (see Figures 3 and 4) is connected, so that all the stump foot cylinders can be supplied with pressure fluid simultaneously.

In the casing forming the body of the junction box provision is made for the simultaneous release of the check valves by means of a plunger having a pad or button FP which may be depressed by theoperators foot. This release of the check valves allows the fluid to return to the sump S (Figures 1, 2, and 4) of the pump P via an additional port and conduit which are connected to it.

A table lift ram LR is provided with a cylinder in the extension having an exhaust passage for pressure fluid from the table lift ram cylinder. The escape of fluid from this passage to the sump is controlled by the pressure release valve PRV which may be a ball check valve normally held to its seat by a spring, but displaceable from the seat by a small plunger when fluid is to be released. This plunger is guided in a bore inthe lower end of an upright cylinder and extends into this cylinder where it is provided with an enlargement or piston. The pressure release valve PRV provides for independent release of pressure fluid from the table lift ram cylinder to the sump S.

A pedal PP is provided which may be arranged to gpierlate both the pump P and the pressure release valve The delivery port from the pump P leads to a passage in the base in which a spring loaded check valve CV (Figure 4) is fitted. This passage interconnects near the opposite end with a delivery pipe through a union. This pipe delivers pressure fluid from the pump through a relief valve RV to the central inlet in the valvecasing VC before referred to. The relief valve is provided with a pipe connected with the table lift ram cylinder.

The pump is operated by the pedal PP which pedal is adapted to actuate a rocker R one arm of which is adapted, when the pedal is depressed, to bear on the cross-head of the pump piston rod. The pedal is also conveniently adapted to operate the pressure release valve PRV of the table lift ram. For this purpose the pedal is lifted so that a second arm on the rocker R engages with and depresses the head of the plunger or operating rod of the release valve.

Safety exhaust ports SP (Figures 3 and 4) are provided near the upper end of the table lift ram cylinder to limit the maximum upward travel of the piston or lift of the table by permitting pressure fluid to escape therethrough when the piston is raised a sufficient distance to uncover or expose the ports SP to the pressure fluid beneath the piston. Deflectors D are provided to deflect the escaped fluid downwardly into the sump.

There follows a more detailed description of the various parts of the invention heretofore mentioned.

The pump P (see Figure 4) comprises an upright cylinder 9 having an open upper end, and a piston '10, the rod 11 of which extends through the open end and has a cross head 12. The lower end of the cylinder 9 is secured to a. base or casing 13 having an inlet port 14 for the cylinder from the sump S, the port 14 being fitted with a check valve 15 and a strainer 16, having spaced apertures 16a (Figure 3) therethrough. Also located in the base 13 of the pump is: a delivery port 17 from the cylinder. The base 13 may be secured to the floor of the sump by bolts 13a and nuts: 13b.

A helical spring 18 surrounds the pump cylinder 9 and abuts at one end against the bottom surface 19 'of the cross head 12 and at the other end against the base 13. The function of this spring will be fully explained herebelow.

The pump is further provided with

guide rods

20, 20 threaded as at 21 at the lower ends thereof and adapted to be inserted in tapped holes in the base 13, and also threaded at the upper end thereof as at 22 for cooperation with double nuts 23 adapted for adjusting the maximum upward travel of the cross head 12 under the influence of the helical spring 18. The cross head 12 is provided with apertures through which the guide rods 20, 20 pass.

The pump piston 10 is provided with a pair of resilient cups, the lower cup 24 being open downwardly and the upper cup 25 being open upwardly. Two oppositely acting cups are provided in this fashion in order that the pump will have a double acting capacity, i. e., on the up stroke of the piston 10 the cup 25 acts to suck oil in through the apertures 26 against the force of the spring 27 normally closing the valve 15, and on the down stroke of the piston 10 the cup 24' acts to force pressure fluid out through the exit passage 17.

Exit passage 17 interconnects with delivery passage 28 located in a centrally extending portion 29 of the base 13. This delivery passage 28 passes below the lift ram mechanism LR and interconnects through a union with delivery pipe 30 (see Figure 1).

Pressure fluid passing out the delivery port 17 must go through check valve CV in order to reach delivery passage 28. Check valve CV comprises a sleeve 31 having a screw threaded portion 32 cooperating with threads 33 formed in delivery pasage 28. The check valve body 34 has an extension 35 of triangular cross section which extends into the bore 36 of sleeve 31. A resilient washer 37 is provided for cooperation with the valve seat 38. A spring 39 abuts against a collar 40 on the valve body 34 and against a spring seat 41 threaded into the passage 28. Spring 39 acts in direction to normally close check valve CV. Thus, for pressure fluid to pass out of the pump through delivery port 17 and into delivery passage 28, the pressure of the fluid must build up sufiiciently to force the valve body 34 off of the valve seat against the action of spring 39.

Another arm 42 of the base member extends radially outwardly from the lift ram LR in manner similar to arm 29. This arm 42 of the base terminates in an enlargement 43 which may be secured to the floor of the sump by bolts 43a and nuts 43b.

Screw threaded into the enlargement 43 is an upright housing 44 for the pressure release valve PRV. This housing 44 terminates in a cylinder 45 in which the release piston 46 operates.

In the lower portion of the housing 44 there is a ball check valve 47 urged against its seat 'by spring 48 which abuts against the lower side of the ball and against a spring seat member 49 screwed into the bottom of the bore 50 in the housing 44 against the resilient gasket 51. The spring seat member 49 has a passage 52 therethrough communicating with exhaust passage 53 in base arm 42, which exhaust passage 53 is open to the cylinder of the lift ram LR through port 54.

The piston 46 has an extension 55 of reduced cross section extending downwardly through oversize passage 56 in housing 44 into contact with the upper side of ball check valve 47'. Ports 57 through the wall of housing 44 interconnect the annular space surrounding the piston extension 55 and the sump S.

A spring '58 located in the cylinder 45 below the piston 46 and abutting against the bottom of the cylinder 45 and against a shoulder on piston 46, together with a spring 59 abutting against the top surface of the cylinder 45 and the bottom surface 60 of the cross head 61 on piston 46, urge the piston 46 and the extension 55 thereof upwardly.

From the above, it can be seen that depressing the cross head 61 will cause the piston 46 and the extension 55 to travel downwardly and unseat the ball valve 47 against the spring 48. The parts in this lower positionopen a passageway from the lower portion of the cylinder of the lift ram LR through the port 54, the exhaust passage 53, the passage 52, the bore 50, the annular passage 56, the ports 57, and into the sump S.

The foot pedal PP is mounted for rotation with an axle 62 which is journalled in and protrudes through the dome-shaped casing or cover plate 63 generally surrounding and overlying the sump S and enclosing the tableram cylinder, the pump, the pressure release valve and the pedal rocker and secured to the base B by screws 64.

The rocker R is forked at each end (see Figure 3) and

rollers

66, 67 are mounted on pins between the tines of the forks. The roller 66 is positioned just above the cross head 12 of the pump and the roller 67 is positioned just above the cross head 61 of the pressure release valve PRV.

With this arrangement, it will be seen that movement of the pedal PP downwardly from the position shown in Figure 2 will tend to build up pressure in the fluid beneath the piston of the pump P, driving fluid out through delivery channel 17. Upon reaching the bottom of the downward stroke, the operator lessens the force on the pedal PP sufiiciently to permit the spring 18 to return the cross head 12 to its upper position. During this upward stroke fluid is drawn into the pump cylinder through the check valve 15 and the pumping cycle may be repeated.

On the other hand, movement of the pedal PP in an upwardly direction as viewed in Figure 2 will depress the cross head 61 of the pressure release valve PRV and thus vent the cylinder of the lift ram LR to the sump. This release of the pressure fluid in the lift ram cylinder lowers the table T and the weight carried thereon.

ass /33w Attention will now be turned to the lift ram assembly. As above mentioned, the cylinder 68 of the lift ram is mounted on the same base as the pump P and the pressure release valve PRV. The cylinder 68 is fitted with a ram or piston 69 having a rod 70 extending beyond the upper open end of the cylinder.

The piston has a downwardly open cup 71 held in place by

cup washers

72 and 73.

A coiled spring 74 below the piston abuts the bottom of the cylinder and a shoulder on the lower end of the piston 69 and acts as a buffer normally holding the piston above the level of the inlet port 75. The upper end of' the rod 76 is secured or located by suitable means to the table to be raised and lowered.

Attention is now called to the relief valve RV best seen in Figure 6. The pipe 30 carrying pressure fluid from the pump by way of the delivery channel 28 interconnects with a passage 7 6 near, the bottom of the relief valve RV through a union 77. Pressure fluid may flow from the passage 76 through the union 78 and out the pipe 79 which leads to the junction box or valve casing VC described herebelow.

An upright portion 80 of the relief valve has a bore 81 interconnecting with the lower passage 76. The bore 81 contains a ball check valve 82 in contact with a plunger 13. A coiled spring 84- abuts at its lower end on a collar 85 on the plunger 83, while the upper end of the spring abuts against a collar 86 on a second plunger 87. By this arrangement, the lower plunger 83 normally holds the ball valve to its seat.

An adjusting screw 88 passes through a nut 89 and the relief valve cap 90 and bears against the top of the second plunger 87. By these means the pressure of the spring 84 and, therefore, the pressure at which the relief opens can be regulated.

A cover 91 protects the upper portion of the relief valve mechanism.

A passage 92 communicates with the bore 81 at a point above the normal (closed) position of the ball check valve 82 and leads through a union 93 to a pipe 94 which carries pressure fluid to the cylinder of the lift ram LR.

During the initial portion of the pumping by means of the pedal PP pressure fluid is supplied to the stump feet through delivery channel 28, pipe 30, and pipe 79 (connected at the bottom of the relief valve RV) and valve casing VC. When the stump feet have been extended into contact with the floor under pressure suflicient to relieve the castors C from all load, back pressure builds up sufliciently to force the check valve 82 into its upward open position and permit pressure fluid to pass out of passage 92 and into the pipe 94 leading to the lift ram.

The arrangement is such that when the pump has supplied sufiicient pressure fluid to operate the stump feet, a few further strokes of the pump will set up sufficient pressure to open the relief valve and supply fluid to raise the table lift ram.

Turning now to the junction box or valve casing VC of Figures 7 and 8, it will be seen that this device is of the nature of a manifold providing simultaneously fluid under equalized pressure to four pipes leading to the stump feet.

The pipe 79 from the relief valve RV connects through a union 95 near the bottom of the valve casing to the lead-in passage 96. The pressure fluid flows through the passage 96 into the manifold chamber 97. Four equally spaced radial passages communicate with the manifold 97. Pressure fluid may flow through these four passages and

appropriate fittings

98, 99, 100 and 101 into

pipes

102, 103, 104 and 105.

A ball check valve is provided in each of the four exit passages leading from the manifold 97. Three of these

balls

106, 107 and 103 appear in the sectional view of Figure 7. A spring such as 109 and 110 associated with each ball holds the ball normally against the seat and concludes backflow from stump feet SF.

A return passage 111 leads upwardly from the mamfold 97 and communicates with a return pipe 112 to the sump S. The return passage 111 has formed at its lower end a valve seating. The plunger rod 113 has at its lower end an enlargement 114 which has a conical upper surface which is normally held by spring 115 against the seating formed at lower end of return passage 111, forming a valve which occludes the passage of pressure fluid from manifold chamber 97 to the return passage 111. When the rod 113 is displaced downwardly the valve opens and the lower surface of the enlargement 114.

simultaneously displaces the four ball check valves as 106 from their seats and pressure fluid is allowed to pass from

pipes

101, 102, 103, 104 through manifold chamber 97 to return passage 111. A foot pad is attached to the upper end of rod 113 and a spring 115 urges the foot pad and rod assembly towards its upward position. cover plate 116 is provided with attachment screws 117 for ease in removing, repairing, etc., the valve casing assembly.

The pipe 102 interconnects with stump foot 118, pipe 103 with stump foot 119, pipe 104 with stump foot 120, and pipe 105 with stump foot 121. Since all four of the stump feet are alike in construction and operation, a detailed description of stump foot 119, referring particularly to Figure 5, will be sufficient.

The stump foot pad 122 is carried on the piston 123 and fastened thereto by means of the threaded portion 124 and the nut 125. A plate or washer 126, for instance of rubber, may be secured by a screw 127 to the bottom surface of the stump foot pad 122 to provide a desirable surface for contact with the floor. Pressure fluid from the pipe 103 may flow through the passage 128 into the stump foot cylinder 129 above the cup 130 on the top of the piston 123.

A spring 131 surrounds the piston 123 and abuts against a shoulder 132 and said piston and against a shouldered boss 134 bolted to the lower surface of the cylinder casting 134a. Spring 139 urges the piston and thus the stump foot toward the upward or retracted position out of contact with the floor.

A contact of the piston body with the boss 134 and also with shoulder 135 of the cylinder limits the upward travel of the stump foot and piston. Downward travel of the stump foot and piston is limited by the

shoulders

132 and 133 and the bottoming of the spring 131 located therebetween.

The stump foot cylinder 129 is provided at the top thereof with a bleeder valve 136, which is normally closed but may be opened when required to allow any air present to escape. A protective cap 137 is fitted over the top of the stump foot cylinder and the bleeder valve.

With the foregoing detailed description in mind, a brief summary of the operation of the invention follows.

When the equipment is in the condition shown in Figure 2, it is readily mobile on the castors C and can be moved from place-to-place at will.

Repeated downward pumping action on the foot pedal PP causes delivery of pressure fluid from the pump P to the relief valve RV. At first the pressure fluid will flow through the relief valve and the valve casing VC, and from there to the four stump feet SF. This results in extending the stump feet into contact with the floor and thus results in the bearing of the load on the stump feet instead of the castors C. The stump feet will be extended greater or lesser distances as may be necessary to compensate for any unevenness in the floor by reason of the pressure equalizing characteristics of the hydraulic system supplied from a common source in the manifold of the valve casing VC.

When the stump feet are extended the pressure will build up in the fluid lines leading from the stump feet to the valve casing VC and thus in the fluid line leading to the relief valve RV. The increased pressure opens check valves (106 and 108) effectively prevent release of pressure in the stump foot cylinders.

When the lift ram is extended upwardly sufficiently far that the safety ports SP communicate with the cylinder below the piston cup 71, no further upward travel of the lift ram is possible since the pressure fiuid escapes through the safety ports SP and returns to the sump S.

If it is desired to lower the table, this can be accomplished without rendering the unit mobile by lifting up on the pedal PP and thus opening the pressure release valve PRV and venting the lift ram cylinder to the sump. It is thus seen that, after the stump feet are initially extended, operating the pedal PP in one direction or the other will adjust the height of the operating table Withoutaffecting the position of the stump feet.

If it is desired to wheel the table to some other location, this can be accomplished by depressing the foot pad PP and thus venting the stump feet cylinders to the sump. This will result in retraction of the stump feet and a reassumption of the load by the castors and this will not affect the position of the lift ram LR because of the occlusion of backfiow by the ball 82 in the relief valve RV. After the table has been moved to the desired location, pumping downwardly on the foot pedal will again extend the stump feet without afiecting the height adjustment.

1 claim:

1. In a base for supporting equipment such as an operating table or the like, said base being movable on a plurality of casters, the combination of a hydraulic lift for altering the vertical position of the supported equipment, a plurality of stump feet for said base vertically movable between retracted positions out of contact with the floor and extended positions in contact with the floor, said stump feet in the extended positions supporting the base independently of said casters, a junction box, a

plurality of fluid passage means between said junction box and each of said stump feet, a plurality of simultaneously operable check valves in said junction box, one in each of said passage means and normally occluding flow in direction to retract said stump feet, a hydraulic pump carried on said base, fluid connections from the pump to the lift and from the pump to the junction box, a relief valve interposed in said last named connections and operable upon extension of said stump feet to deliver pressure fluid to the lift, means for releasing the pressure to said lift, and means for disabling; said check valves independently of the release of pressure to said lift.

2. A mobile unit for supporting equipment such as an operating table or the like, comprising a base member, a plurality of stiunp feet mounted therein and adapted to immobilize said unit, a lift ram for altering the vertical position of the supported equipment, first fluid pressure piston and cylinder means operable to condition said stump feet to immobilize said unit and second such means operable to raise said lift ram, a pump and a sump for supplying fluid thereto, pressure fluid delivery means interconnecting said pump and said first and second piston and cylinder means, valve mechanism in said delivery means adapted to permit flow to said second piston and cylinder means to raise said lift ram automatically upon completion of operation of said first piston and cylinder means to immobilize said unit, and return connections from said first and second means to the sump of said pump.

3. The mechanism of claim 2 wherein the pressure fluid delivery means interconnecting the pump and the first piston and cylinder means includes a common manifold for effecting hydraulic leveling of the stump feet in said cylinders.

4. A construction according to claim 2 in which said first means comprises a plurality of piston and cylinder devices, one associated with and adapted to extend and retract each of said stump feet, and said construction further including a junction box interposed in the delivery means interconnecting the pump and said first means, said junction box comprising manifold means having an intake from the pump, a plurality of discharge outlets, each connected with one of the piston and cylinder devices, and a return outlet connected with the sump of the pump, a spring loaded check valve in each discharge outlet normally occluding flow in direction to permit retraction of the stump feet, obturating means normally closing said return outlet, and actuating means positioned to simultaneously displace said check valves and said obturating means.

5. A construction according to claim 4 in which said obturating means comprises a valve device, said check valve in each discharge outlet comprises a ball protruding into the path of travel of said valve device and adapted to be displaced from its valve seat thereby, and in which said actuating means is spring loaded to hold said valve device in a position obturating flow through said return outlet and is adapted to displace said valve device.

6. A mobile unit for supporting equipment such as an operating table or the like, comprising a base, a plurality of stump feet mounted therein and adapted to immobilize said unit, a lift ram for altering the vertical position of the supported equipment, first fluid pressure piston and cylinder means operable to condition said stump feet to immobilize said unit and second such means operable to raise said lift ram, a pump and a sump for supplying fluid thereto, pressure fluid delivery means interconnecting said pump and said first and second piston and cylinder means, valve mechanism in said delivery means adapted to permit flow to said second piston and cylinder means to raise said lift ram automatically upon completion of operation of said first piston and cylinder means to immobilize said unit, and independently actuated control devices for venting said first and second piston and cylinder means to the sump of said pump.

7. A construction according to claim 6 and further including a pedal mounted on one end of an axle and operable to rotate said axle in either direction from a neutral position, journal means for said axle connected with said base, a double ended rocker arm mounted on the other end of said axle, one end of said rocker arm being adapted upon rotation of said axle in a given direction to operate said pump, and the other being adapted upon rotation in the opposite direction to operate said control device venting said second piston and cylinder means to the sump of the pump, and balanced spring means opposing rotation of said axle in either direction and adapted upon release of force displacing said pedal to return same to the neutral position.

8. A mobile unit for supporting equipment such as an operating table or the like, comprising a base member, a plurality of stump feet mounted therein and adapted to immobilize said unit, a lift ram for altering the vertical position of the supported equipment, first fluid pressure piston and cylinder means operable to condition said stump feet to immobilize said unit and second such means operable to raise said lift ram, a pump and a sump for supplying fluid thereto, pressure fluid delivery means interconnecting said pump and said first and second piston and cylinder means, valve mechanism in said delivery means comprising a check valve normally biased toward a position occluding flow in the delivery means interconnecting the pump and the second piston and cylinder means but displaceable to permit such flow in direction to raise said lift ram when the pressure in the fiuid exerts a force exceeding that of said bias, and independently actuated control devices for venting said first and second piston and cylinder means to the sump of said pump.

References Cited in the file of this patent UNITED STATES PATENTS 10 Klipstein et a1 Nov. 11,1941 Shampaine Feb. 25, 1947 Clachko Aug. 29, 1950 Shampaine Dec. 5, 1950 Gardiner Oct. 30, 1951 Shampaine July 29, 1952 Murray Apr. 28, 1953 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.. 2,837,387 June 3, 1958 Ernest Gordon Greville 7 It is hereb$ certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5, line '75 for "concludes" read occludes column 6, line 3'7,'for "and", first occurrence, read on Signed and sealed this 22nd day of July 1958,

(SEAL) Attest:

' ROBERT C. WATSON Attesting Officer Commissioner of Patents