TRANSACTIONS OF SECTION A. 553 



17. Design for luorking the Equatorial and Dome of ' Lick ' Observatory, 

 California, by Hydraulic Power. By Howard Gkubb, F.B.S. 



In the case of very large astronomical telescopes it is desirable to relieve the 

 ■observer as much as possible from the great physical exertion required to work the 

 instrument, dome, observing chair, &c. 



The author has worked out a system of hydraulic machinery which effects all 

 the necessary operations and at the same time brings them under the complete 

 control of oue individual. 



This was illustrated by a working model in which the hydraulic apparatus 

 was represented by clockwork governed, as in the case of the actual apparatus, by 

 •electricity. 



WEDNESDAY, SEPTEMBER 8. 



The following Papers were read : — 



1. The Advantages to the Science of Terrestrial Magnetism to be obtained 

 from an expedition to the region within the Antarctic Circle. By Staff 

 Commander Ettkick W. Creak, B.N., F.B.S. — See p. 98. 



2. On Lithanode. By Desmond G. Pitz-Gerald. 



It is claimed for this substance that it is the negative element par e.vcellence for 

 Toltaic batteries, primary or secondary, and also a perfect anode for the electrolytic 

 separation of the most electro-negative elements, e.g., chlorine. No other substance 

 fulfils all the desiderata for a negative voltaic element, and no other substance that 

 can be generally employed as an anode in electrolysis is unattackable by chlorine. 

 Lithanode is peroxide of lead in a dense, coherent, and highly conductive form. It 

 ■constitutes a step in the series of inventions, initiated by Plants and continued by 

 Faure, Volckmar, and others, by which the secondary battery has been perfected. 

 By this step local action in the negative element, a defect of all secondary batteries 

 excepting those constructed with lithanode, is entirely precluded. Lithanode is 

 obtained by moulding a plastic mass of oxide of lead with the solution of a salt, 

 such as ammonic sulphate, which is gradually decomposed by the oxide of lead. 

 The effect of the gradual chemical action is to cause the substance to ' set,' and to 

 acquire a high degree of cohesion and hardness. The mass is then electrolytically 

 converted into a peroxide of lead differing from other forms of this substance, and 

 withstands perfectly the processes of ' charging ' and ' discharging,' however rapidly 

 these may be effected. 'The advantages attending the use of lithanode in secondary 

 batteries are — 1, a permanent negative element; 2, economy of power; and 3, 

 diminished weight. The advantage in commercial processes of electrolysis is that 

 lithanode constitutes a cheap electrode, and the only one not attackable by 

 chlorine. 



3. Draper Memorial Photographs of Stellar Spectra exhibiting Bright Lines. 

 By Professor Edward C. Pickering. 



The spectra of ordinary stars, whether examined directly by the eye or 

 indirectly by means of photography, present little variety. The comparatively 

 few cases of deviation from the usual type are therefore particularly interesting, 

 and the occurrence of bright lines in a stellar spectrum constitutes perhaps the 

 most singular exception to the general rule. The brightness of the F line in the 

 spectra of y Cassiopeise and fi Lyrte was noticed by Secchi. Rayet afterwards 

 found three rather faint stars in Cygnus, the light of which was largely concen- 

 trated in bright lines or bands. The adoption at Harvard College Observatory of 



