344 SEC. 11. ASTRONOMY. 



1765. Pour-inch Achromatic Telescope, on altazimuth 

 stand, with quick and slow motions, in altitude and azimuth. 



John Browning. 



1766. Instrument for Easy Determination of Time by 

 Equal Altitudes of Different Stars. 



Colonel Zinger, Pulkowa. 



This instrument is constructed for easy application of the method developed 

 lately by Colonel Zinger for exact determination of time by equal altitudes of 

 different stars (see Viertelgebrschrift des Astronomischen Gesellschaft, 1875). 

 The principal condition is unaltered relation of level to telescope in going over 

 from a star in the east to another in the west by having found its vertical axis. 

 The divided circles serve only for setting the telescope. For using only bright 

 and well determined stars down to the (3 or 4) magnitude, 9 minutes of time 

 will be in the average sufficient to give time with the accuracy of 0' 1 s . The 

 eye-piece of the telescope is provided with a micrometer, to enable the 

 observer to get with the same instrument, by approximately equal altitudes of 

 two stars near the meridian, exact determination of latitude. 



c. TRANSIT CIRCLES AND QUADRANTS. 



1767. Meridian Circle, with object glass of 6" aperture and 

 6' focal length. Circle of 2' diameter under construction for the 

 Observatory of Strassburg? (Photograph.) 



A. Repsold and Sons, Hamburg. 



(5.) In this instrument the microscopes are attached to the heads of the 

 cast-iron columns, which also bear the bed-plates. One of the pivots carries 

 an objective (2" aperture), and^ the other a plate with a bored hole ; this 

 arrangement serves, at the suggestion of Prof. Winnecke, as a collimator for 

 controlling the position of the axis. Perfectly centralillumination of the field 

 of view is effected by a small mirror at the back of the objective. The heads 

 of the objective and eye-piece can be changed in the heads of the telescope, 

 and there is an arrangement for Nadir observations, also for reflex star 

 observations with a Nadir distance of 8-60 by means of a movable 

 mercurial horizon. 



1768. Transit Instrument, with azimuth circle, a broken 

 telescope of 3" aperture. (Photograph.) 



A. Repsold and Sons, Hamburg. 



When the instrument , is inverted, which can be very [quickly effected, 

 the level and lamp remain hanging, and the binding-screw need not be 

 loosened. There is a microscope for the eye-piece. 



1769. Transit Instrument, with straight telescope of 3-3" 

 aperture. (Photograph.) A. Repsold and Sons, Hamburg. 



In inverting it is not necessary to .loosen the binding screw, and the 

 level remains in position. A microscope is attached to the eye -piece. 



