US285907A - Protractor - Google Patents

Description

(No Model.)

P. KENNELLY.

PROTRAGTOR. No. 285,907. Patented Oct. 2, 1883.

e'nds which are UNITED STATES PATENT Crrrcie.

PATRICK KENNELLY, OF BRIDGEPORT, CONNECTICUT.

PROTRAC'TOR'.

sencrrrcn'rron forming part of Letters Patent No. 285,907, dated October 2,1883.

Application filed February 20, 1583. (No model.)

To all whom it nmyconcern:

Be it known that I, PATRICK KENNELLY, a citizen of the United States, residing at Bridge port, in the county of Fairfield, State of Connecticut, have invented an Improved Protraetor, of which the following is a specification.

My invention relates to that kind of a protractor in which there is a revolving center and a straight edge, whereby machinists and other artisans may use their plain bevel-square in determining the different angles.

' The object of my invention is to provide a tool for accurately determining all angles, in connection with the common bevel-square, which is a part of the usual outfit of all ironworkers.

In the drawings forming a part of this specification, Figure l is a plan view of the protractor graduated from ninety degrees at right angles to the base-line a b to 0 at each of the parallel to the baseline, substantially as shown. Fig. 2 is an edge view of Fig. 1. Fig. 3 is an enlarged view ofswive1- center. ,Fig. at is an enlarged cross-section of Fig. 3, showing the upper portion out to the center at a. Figs. 5 and 6 are a plan and elevation of screw for fastening Fig. 3 to Fig. 1, as shown in Fig. 2 at b.

To operate the device it is only necessary to place one edge of the bevel-square on the edge a b, Fig. 1, then bring the blade against the face of that part of Fig. 3 which is shown in cross-section at a, Fig. 4.. found that the blade will stop in the center and register the angle accurately on either side of the perpendicular.

I am aware that prior to my invention protractors have been used by draftsinen and others; those, however, cannot be used by inachinists, tool-makers, and a large class of other tradesmen, each of whom have a plain bevelsquare, which, with the use of my invention, will enable them to use it to advantage; but I am not aware that any with a revolving se1f-adjusting center has been used therefore I claim- 1. The combination of the revolving center, Fig. 3, the upper part of which is cut away to the center, as shown, and the graduated are, as and for the purpose described.

' 2. The combination of the graduated arc, Fig. 1, and self-adjusting center, Fig. 3, one half of which is removed to the center, as shown at a, Fig. 4, with edge of Fig. 1, so that the center will adjust itself to any angle de sired, substantially as shown.

PATRICK KENNELLY.

It will then be

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