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595,261 · Basquin · "Device for Selecting Prisms Having Proper Angles" · Page 2 Home  > Prism Glass  > Patent Index  > Page 2

595,261: 2 of 5

which is in turn connected with the fixed pivot I4, preferably in line with the graduation E³ and the pin F. The guide I² is also pivotally connected with the pointer L, adapted to be moved along the graduated arc and pivotally connected with the pin F. The part L' of the pointer L is equal in length to the arm I³, and the parts are so arranged that the guide I² is parallel to itself in all its various positions, or, in other words, has a movement of translation. The arc E is cut away or formed so that the guide I² may move freely thereunder. The pointer L is preferably provided with means whereby it may be fastened in any desired position. This result may be obtained in any desired manner. As illustrated in the drawings, the pointer is split at the end, as shown in Fig. 4, the arc passing between the split portions. A thumb-screw L² engaged these split portions and compresses them, so that they will grasp the arc, and thus be held in any desired position. I have shown the pointers G and L as working upon the same scale; but it is of course evident that separate scales might be used, if desired.     I have shown a particular construction embodying my invention and have described the parts in detail; but it is of course evident that the parts may be varied in form, construction, and arrangement without departing from the spirit of my invention, and I therefore do not wish to be limited to the construction shown.     In using the device as illustrated in the drawings I moved the pointer H along the scale H' until it indicates the index of refraction of the glass. The scale H', as illustrated in the drawings, is divided into tenths. In Fig. 1 the pointer is set at "1 5/10" and in Fig. 2 at "1 7/10." The pointer is held in the desired position by tightening the thumb-screw H². The pointer L is then moved along the arc until it is opposite the graduation representing the angle at which the light enters the prism, and the thumb-screw L² is then tightened, so as to hold the pointer L in place. The pointer G is then moved opposite the graduation on the scale E, which represents the angle at which the light leaves the prism. The pointer F4 then indicates on the scale E4 the angle of the prism to be used— namely, the angle D. This angle is then readily and easily read from the scale.     In Fig. 1 I have set the instrument for a glass having an index of refraction of one and five-tenths, the light entering the prism at an angle of forty degrees and leaving the prism at an angle of zero— namely, in a horizontal direction. Under these conditions the pointer F4 shows that the angle of the prism is sixty degrees.     In Fig. 2 the index of refraction of the glass is one and seven-tenths, the light entering the prism at an angle of seventy-five degrees and leaving the prism at an angle of ten degrees above the horizontal. Under these conditions the pointer F4 indicates that the angle of the prism to be used is sixty-six degrees.

When the light is to leave the prism above the horizontal, the pointer G is moved to the right of the graduation E³, and when the light is to leave the prism below the horizontal said pointer is moved to the left of said graduation.     I claim—     1. A device for finding the angles of prisms, comprising an indicating device adapted to be set so as to indicate the index of refraction of the glass, a second indicating device adapted to be set so as to indicate the angle at which the light is received, a third indicating device adapted to be set so as to indicate the angle at which the light leaves the prism and a pointer associated with said indicating devices adapted, when the indicating devices are set, to indicate the angle of the prism to be used.     2. A device for finding the angles of prisms which will throw the light toward a given point when it is received from a given direction, comprising a series of indicating devices adapted to indicate upon suitable scales the conditions to be met, a pointer adapted to indicate upon a suitable scale the angle of the prism, said pointer provided with two slots substantially at right angles to each other and connected with said indicating devices by a series of sliding blocks working in said slots.     3. A prism-angle-indicating device provided with a series of indicating devices adapted to indicate the conditions to be met, said indicating devices comprising a pointer adapted to indicate upon a suitable scale the angle at which the light is received, a pointer adapted to indicate the angle of the prism, and a parallel-moving arm connecting said two pointers together.     4. A device for finding the angles of prisms, comprising a graduated arc, a series of indicating devices pivotally connected at the center about which the arc is described, a pointer adapted to point out the angle of the prism to be used on said gradated arc and connected with the center about which the arc is described, said pointer connected with said indicating devices so as to be controlled thereby.     5. A device for finding the angles of prisms, comprising a graduated arc divided into degrees, a pointer connected with the center about which said arc is described and adapted to be moved along said arc to indicate the angle at which the light is received, a second pointer pivotally connected with the center about which said arc is described and adapted to indicate on the arc the angle at which the light leaves the prism, a pointer connected with both of said pointers and adapted to indicate on a suitable scale the index of refraction of the glass of which the prism is made, and an indicator connected with said pointers and adapted to move along said arc and