MISCELLANEOUS. 1057 



two movements will combine into one, which, according as the respective 

 longitudinal relations of the two strips are altered .will be different. By the 

 brad attached to the upper part of the apparatus these movements can be 

 clearly observed, and Lissajou's figures demonstrated. 



4447. Meyerstein's Heliostat. 



4448. Astronomical Telescope, on a wooden stand with 

 scale. 



4449. Pocket Spectroscope, according to Professor Ems- 

 mann, with only one prism, and contrivance for specially placing 

 the separate colours. 



4450. Another Specimen of the same kind. 



4451. Thermo-electrical Battery, according to Clamond. 



This consists of 40 elements, which are arranged in four groups, which can 

 be placed either side by side or one after the other. The heating of the 

 soldered places takes place from the centre by gas, but not directly, however, 

 by heated air generated in the interior of the battery. The gas turns from 

 small holes made round a clay cylinder. For an equal supply of gas, par- 

 ticularly in order to avoid at a stronger pressure an excessive heating of the 

 soldered places, an ordinary gas regulator with floats, as is customary with 

 gas meters, has been attached. If the supply of gas increases the valve 

 closes, opening again at the decrease of pressure. As, consequently, the 

 supply of gas regulates itself in this way, the column uninterruptedly acts for 

 weeks and months, while its current is extremely constant at an effective 

 force of 5 cc. oxygen and hydrogen gas a minute, and is therefore particu- 

 larly adapted for the quantitative separation ofmetals from solutions. 



As regards the durability of the apparatus, it may be remarked that after 

 18 months daily use, no perceptible alteration has been noticed. 



4452. Thermo-electrical Battery, according to NoeX 



This differs from the previous one, 



1, by the arrangement of the metals, which in this case are grouped in two 

 horizontal rows, in the centre of which (and this is the second essential dif- 

 ereiice) a number of burners heat the soldered places directly. The cooling 

 of the other soldered places is, as in the previous battery, simply atmospheric, 

 for which purposes, in order to render it as perfect as possible, copper plates 

 are connected with the other soldered places, so that a constant current of air 

 passes through the same. 



The number of elements is 88, grouped into 8 elements, which by means 

 of a very handy pachytrope can be intercalated in different manner. 



4453. Lane's Measure-bottle, fine adjustment, with scale 

 and vernier. 



4454. Separable Leyden Jar. 



4455. Electroscope, after Professor Mach, for demon- 

 strating that electricity lies on the surface of excited bodies. 



40075. 3 X 



