#A150. Positive Eye Pieces.# (Ramsden), focus 6 mm. to 25 mm. Price #$4.50# #A151. Negative Eye Pieces.# (Huygenian), focus 5 mm. to 25 mm. Price #$4.50# #A152. Diagonal Eye Piece.# The prism of the eye piece has guaranteed optically plane surfaces and will not affect the definition of the telescope. Price #$12.00# #A153. Terrestrial Eye Piece#, focus 25 mm. Price #$12.00# #A154. Sun Caps#, to fit above eye pieces. Price #$1.50# The outside diameter of all our eye pieces is 1 1/4" excepting those used in our Micrometers. [Illustration: A 201] #A201. Position Micrometers for 6" to 8" Telescopes.# Circle 15 cm. diameter, divisions on solid silver, verniers reading to 6 min., slow gear motion for rotating, electrical illumination, provided with different color screens. Screw guaranteed of highest accuracy. Price #$200.00# #A202. Position Micrometers for 4" to 5" Telescopes.# Similar to above but rotation by hand and construction somewhat simpler. Price #$100.00# [Illustration: A 203] #A203. Small Position Micrometer for 3" to 4" Telescopes.# Circle reads to single degrees. Electric illumination. Price #$75.00# [Illustration: A 301] #Transit Instrument#, with reversing arrangement, illumination with oil or electric lamp, Filar micrometer with two eye pieces. Weight of axis balanced by springs and rollers. The circle has a diameter of 150 mm., verniers read to 20 seconds. The instrument is mounted on an iron base plate, which is fitted with azimuth adjustment (not shown in cut). #A301. Transit# with 2" Telescope. Price #$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]