#$550.00#

#A302. Transit# with 3" Telescope. Price #$800.00#

[Illustration: 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.

[Illustration: 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#

[Illustration: A 601]

[Illustration: A 602]

#A601. Small Spectroscope.# Suitable for telescope from 3 to 6 in.
aperture. The collimator and observing telescope have an aperture of 25
mm., focus of 200 mm. Both are fitted with rack and pinion. The
spectroscope may be used with a grating or a 60 degree prism, and for this
purpose has openings fo