A 401
| A401. Universal Instrument. Telescope with objective prism. Vertical circle has a diameter of 13 cm. is divided to 10 min. and reads by means of two micrometer microscopes to 10 sec. The telescope is fitted with hard phosphor bronze bearing rings and is reversible. Aperture of objective is 30 mm. Two eye pieces are furnished giving magnification of 20 and 30 diameters. The prism has absolutely plane surfaces and will not affect the definition. Striding level reads to 2 sec. The horizontal circle is protected and reads by means of two verniers to 1 min. The instrument is packed in a light but strong case. Price complete with tripod | $420.00 |
Note.—This instrument was first constructed for Mr. E. de K. Leffingwell, who has found it very satisfactory for his work in the polar regions.
A 501
| A501. Zoellner Astrophotometer. The instrument is made to attach to the eye end of the telescope and may be used with any size of refractor or reflector. An axis parallel to the telescope tube allows the instrument to rotate as a whole. A clamp is provided to hold it in position. The artificial star is formed by a small incandescent lamp which is adjustable in any direction, and in front of which is mounted a small diaphragm. The color changing device, consisting of Nicol prism and quartz plate, is fitted with a divided circle reading to single degrees. The circle revolving with the Nicol prism for changing the intensity of the star, has a diameter of 14 cm. and reads by means of two verniers to 6 min. A concave lens is mounted in the path of the artificial star to make the light diverging at the proper angle and a plane parallel plate is adjustably fixed in the center of the box in order to throw the light in the eye piece. An achromatic objective in front of the eye piece brings the images of the real and artificial star to a focus in the same plane. Price | $150.00 |
A 601