378 SEC. 11. ASTRONOMY. 



constellation preserves its proper form, for the representation is conformable, 

 that is, proportional in the smallest parts. There is no want of conformity at 

 any point, not even at the poles, so that even there the meridians cut each 

 other at the correct angle. By this means the spherical form is always 

 pictured to the eye ; the arrangement of the map is easily imagined, by 

 supposing an elastic envelope to be stretched about a celestial sphere, then cut 

 open and stretched on a frame. The course of the milky-way which follows 

 one of the great circles of the heavens, and the parts comparatively free from 

 stars which are at the poles of this great circle, are very well represented by 

 means of this map. The map contains the stars from the first to the sixth 

 magnitude. 



The mathematical considerations which are necessary for accurately under- 

 standing the construction of the map will be found in the accompanying 

 treatise : Ueber eine 'conforme Abbildung der Erde nach der epicycloidischen 

 Projection. (Extract from the Zeitschrift fur Erdkunde, Vol. IX., Berlin, 

 1874, published by Dietrich Keimer. 



1919. Treatise on a Conformable Representation of the 

 Earth by Epicycloidal Projection. (Extract from the Zeit- 

 schrift fur Erdkunde, vol. IX., Berlin, 1874.) 



Dr. F. August, Berlin. 



XL MISCELLANEOUS. 



1920. Vinot's Siderpscope. T. and A. Molteni, Paris. 



1921. Apparatus, constructed by Professor Kaiser, for deter- 

 mining the absolute value of personal errors in observations on 

 the transit of stars. 



H. G. Van de Sande Bakhuysen, Director of the Observa- 

 tory at Ley den. 



The moment of the transit is registered by the action of a current. The 

 construction of this instrument dates from 1858 ; the first observations were 

 taken in 1859. (Dutch Records, Tome I., p. 193.) 



1922. Observing Seat for Reflecting Telescopes, in- 

 vented by the contributor. E. B. Knobel, F.R.A.S., F.G.S. 



The observer sits as on horseback, and by simply raising himself off the 

 seat, standing on the ground or on the movable footrests, as if in his stirrups, 

 he can easily pull the seat up under him, and adjust it to the required height, 

 without dismounting or moving from the eye-piece of the telescope. Releasing 

 the ratchet wheel allows the seat to be lowered to any position. 



1922a. Collection of Compounds of Silicon with various 

 Metals for optical purposes. 



1922b. Fittings for Astronomical Telescopes. 



M. Lutz, Paris. 



1923. Cooke's Lamp for illuminating the micrometric spider 

 webs of astronomical telescopes. A. A. Pearson, Leeds. 



The lamp is inserted in the brass body of the instrument, where it is held 



