containing chamber disposed at the focus of the said curved side, substantially as described.

4. An invention of the character described, comprising cylindrical glass rods each provided with a longitudinal angular groove, a suitable light refracting material contained within and filling said groove and a longitudinal fluid-containing chamber adapted to receive rays of light refracted from said material.

5. An invention of the character described, comprising cylindrical glass rods each provided with a longitudinal angular groove having a curved side and a suitable light refracting material contained within and filling said groove and a fluid containing chamber I disposed at the focus of the curved side.

6. An invention of the character described, comprising cylindrical glass rods each provided with a longitudinal angular groove,

having a curved side, suitable light refracting material contained in and filling said groove, a fluid-containing chamber disposed within said rod and at the focus of said curved side, the outer surface of said material and said chamber conforming in shape to that of the rod, whereby the whole has, in cross section, a circular outline.

7. An invention of the character described, comprising cylindrical glass rods each provided with a longitudinal angular groove having one flat and one curved side, said curved side being provided with lens-like projections extending transversely thereof.

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.

Witnesses:

J. M. NESBIT,

F. L. RAND.