US1945713A - Compass - Google Patents

Description

Feb. 6, 1934. s. WENDELL COMPASS Filed DEC. 10, 1930 m W612? or A576 gaeZ as' fliforzzeys,

Patented Feb. 6, 1934 UNITED STATES COMPASS Samuel I. Wendell, Chicago, Ill.

Application December 10, 1930- Serial No. 501,283

1 Claim.

This invention relates to magnetic compasses and its object is to provide a light weight compass having a readily demountable needle so that the device may be carried conveniently in the pocket while at the same time permitting the needle to be of such proportions as to be quite sensitive in use. Another object is to provide a compass of the character indicated which shall be very economical to manufacture and so arranged as to retain its magnetic qualities over a long period of time. The invention consists of certain elements and features of construction herein shown and described, as indicated by the claim.

In the drawing:

Figure 1 is a side elevation of a compass embodying this invention with the parts arranged in position for use.

Figure 2 is a top plan view of the same.

Figure 3 is a side elevation of the compass with the needle dismounted and enclosed in the carrying case.

Figure 4 is a detail view of the needle and pivoting means corresponding to the modification shown in Figure 5.

Figure 5 is a modified form of the invention combining the compass with a pencil.

Figure 6 illustrates a modification in the form of the needle itself.

Figure 7 is an axial section of a different form V of compass embodying this invention.

Figure 8 is an enlarged detail section of a modification of the structure shown in Figure 7.

As illustrated in Figures 1, 2 and 3, this compass is extremely simple and consists merely of a magnetic needle member, 1, and a hollow tubular case, 2, the latter having at one end a convex bearing surface, 3, which may be formed of any suitable material such as a commercial jewel or as a non-magnetic metallic plug, 4, of the type shown in Figure 4. The tubular case, 2, is fitted with a clip, 5, for retaining it in the pocket of a garment and may have a removable cap, 6, giving access to its interior. When not in use the magnetic needle, 1, is carried within the tubular case, 2, as indicated in Figure 3, and to employ the compass for ascertaining direction it is only necessary to remove the needle from the case, 2, and place it in approximately balanced position on the spherical bearing surface, 3.

The needle is slightly bent so that its center of gravity is thus disposed somewhat below the bearing surface, 3, which tends to stabilize the needle thereon while permitting it to rotate freely about the vertical axis of the convex surface, 3, (which is substantially the axis of the tubular case 2) if the latter is held upright in the hand. The curvature of the needle, 1, also tends to prevent it from rolling ofi the bearing surface, 3, even if the needle be made of round wire stock. If preferred, it may be constructed of fiat material. Preferably the north-seeking end of the magnetic needle, 1, is coated half-way or otherwise treated to give it a color contrasting 5 with the remainder of the needle body to insure correct interpretation of its position when functioning as a compass, and also to substantially designate the approximate center of suspension of the needle. m

This relation of the center of gravity to the bearing surface of the needle is indicated in Figures 4 and 6 by the dot-dash line, X-X, which may be understood as passing through the center of gravity of the needle member in each of the 75, forms illustrated. Figure 4 illustrates a curved needle, 1*, slightly shorter than that shown in Figure 1 and Figure 6 shows a straight needle, l with its end portions, 1, bent down at right angles to lower the center of gravity and effect the desired stabilization. Any of these forms is suitable for use with the tubular carrying case, 2, to constitute a portable pocket compass.

Figure 5 shows a tubular case, 2 mounted on the upper end of a pencil, '7, making a combination tool and providing carrying space for the compass needle, 1 when the latter is not in use.

In this form the convex headed plug, 4, is shown threaded into the upper end of the tube, 2, so as to serve as the removable cap for giving access w to the tube when the needle, 1, is removed therefrom for use.

Figure 7 illustrates a compass having a relatively fiat cylindrical case, 20, with a rectangular window, 21, of limited circumferential extent in its annular wall. The magnetized compass needle, 22, may consist of two members suitably secured in a central bearing yoke, 23, which rests on the convex end, 24, of a bearing screw, 25, set in the bottom wall of the case, 20. An annular m0 jewel, 26, is held between the inner ends of the two arms of the needle in the yoke, 23, with its central opening substantially centered over the bearing, 24, and a center pin, 27, is anchored in the top wall of the case in position to engage in the opening of the jewel, 26, for holding the compass needle in position on its bearing screw, 25.

For observation through the window, 21, the needle, 22, supports an annular dial member, 28, which may have any desired graduations and 11.0

tially the same manner as in Figure '7, but this arrangement tends to carry the center of gravity of the magnet assembly somewhat lower than'the arrangement of Figure 7.

One advantage of the demoun table type of needle and the tubular carrying case shown in Figures 1 to 5 is that the tubular case whichmay be understood. as being made of magnetic material, will act as a keeper for the needle by contact with opposite ends of the latter when it is placed in the tube. If the tube is made of nonmagnetic material as indicated at 8 in Figure 5 it may be furnished with a tubular liner of thin sheet steel or other magnetic metal to function as the keeper, the inner tubular element, 2*, of Figure 5 serving this function.

I claim:

A pocket compass comprising a magnetized needle and a tubular case'to enclose the needle when not in use, said case including a closure and being provided at one end with an externally convex bearing surface on which the needle may be balanced, the end portions of the needle being bent downwardly from its middle portion so that when said middle portion rests on said bearing surface the center of gravity of the needle is below the point of support and it can swing pivotally thereon in response to magnetic attraction without requiring any other means to retain it on the bearing.

SAMUEL I. WENDELL.

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