ECLIPSES OF THE SATELLITES OF JUPITER. ]£3 



employing it as a graduation house during the eight month3 as a graduation 



in which it is not used for crystallization. He has found, n0USP > 



that, all other circumstances being the same, the evapora- and is much 



lion eoes on nearly twice as fast in it as in the common gra- superior to the 

 . " . . , r Ti . v A v . common one. 



duation house with faggots. It is necessary however, that 



the brine should be of the strength of 4° or 5° before it is 



brought thither, otherwise the ropes would speedily rot. 



This building with ropes, the only one in existence, is Dimensions of 



90 met. [295 feet] long, 17 met. [55} feet] of which are the building. 



taken up by the pillars and the machine. It is divided into 



six arches, by party walls covered with boards ; and each 



arch contains 40 troughs, and consequently 2000 single 



ropes 8*3 met. [27*2 feet] long; so that there are in all 



12000 ropes, making a total length of 99600 met. [326546 



feet]. Little expense is required for repairs, as tjiree fourths 



«f the ropes last seventeen or eighteen years from the time 



they are put up. 



XII. 



Eclipses of the Satellites of Jupiter, observed by Johw 

 Goldingham, Esq. F. R.S., and under his Superintend- 

 ence, at Madras, in the East Indies*. 



ETWEEN the beginning of the year 1794 and the end Eclipses of Ju- 

 of the year 1802 Mr. Goldingham had 151 observations of P iter ' s satel " 

 eclipses of the first satellite of Jupiter, and 105 of the se- 

 cond satellite, either at their immersion, emersion, or both. 

 Of these he has given tables, noting the day, whether im- 

 jnersion or emersion, apparent and mean time of observa- 

 tion, time by the Ephemeris, longitude of Madras by the 

 tables, and circumstances of weather, &c. As the judicious 

 remarks prefixed to these tables may be of use to future ob- 

 servers, it will not be unacceptable to several of our readers 

 to find them here. They are as follows. 



The eclipses of the satellites of Jupiter were observed Telescopes, 

 with achromatic telescopes, by Dollond, of three feet and 

 half focal length, and magnifying power between 70 and 



* Phil. Trans, for 1808, p. 322s 



SO; 



