tti Injifutntni for exhibiting Jupiter and hu Motnti 



Jcid ofBenzoiUf 



WHICH is commonly known by the name of flowers of benjamin, is not liable to br 

 eafily adulterated. 



• The bed flowers of benjamin are brilliant white, pofl^efs a peculiarly grateful finell, are 

 totally foluble in boiling water and ardent fpirit, and leave no refidue or aflies w^en laid 

 upon a red-hot iron, or on ignited coals. 



A Model propopd for the ConJlruETion ofaSatdlitian, or Injlrument for explaining the Phtnomenm 

 of Jupiter and his Satellites, with an Account of its Ufe. By the Rev. W. PEARSON, of 

 Lincoln *. 



OINCE the dodlrine of brlghtnefs has been particularly attended to by Mr. Herfchell ia 

 liis obfervations of the heavenly bodies, this celebrated aflronomer has been able, by means 

 of {he excellence of his telefcopes, to announce to the world, what his predeceflbrs could 

 only conje£lure, not only that the fatcllites of Jupiter have each a rotatory motion on their 

 axes, but alfo the exa61 time of each rotation. In Part II. of the Philofophical Tranfac- 

 tions of the Royal Society of the lad year [1797], is an article in which Mr. Herfchell has 

 proved, I think, in a fatisfa£lory manner, that each of thefe four fatellites has, like our 

 moon, jufl; one rotation in every periodical revolution round its primary, viz. The firft or 

 neareft, in i day 8 hours and 26x0- minutes ;. the fecond, in 3 days 13 [by a typographical 

 error made 18] hours and l^^a minutes ; the third, in 7 days 3 hours and 59^5 minutes ;. 



and the fourth, in 16 days 18 hours and 5-rV minutes. This difcovery of a rotation in 



each revolution renders die analogy fo ftriking between the Jovian, as a detached part of 

 the folar fyftem, and that of our own earth and moon, that we can hardly any longer doubt 

 whether or not Jupiter be inhabited. Such a confideration, in my opinion, renders the 

 Jovian portion of the folar fyftem a fubjedl which merits more particular attention than is 

 ufiially allotted to it in Ie£lures upon aftronomy ; and on this account I have contrived the 

 model of an inflirument of a fimple conftruflion for the purpofe of explaining the different 

 phenomena thereof, which, for want of a more appropriate name, I fhall take the liberty 

 of calling a fatellitian. Other inflruments to anfwcr the fame purpofe may have been 

 conftrucled and ufed •, but as I have no kttowledge of any, except that Mr. Rowley's grand 

 ortery is faid to reprefent Jupiter's fatellites moving by wheel-work f, I feel myfelf war- 

 ranted in prefenting to the public a plan and defcription'of the conftituent parts of this 

 detached inftrument, and of the method of ufing it, in hopes that it may prove not unao- 

 ceptable to the cultivators of fcience, or at leaft that it may fuggeft to fome more inge- 

 nious artift the means of making a more eligible one, 



• Gommunicated by the author. 



■^ A macfiine for this purpofe is alfo defcrlbed in Harris's Lexicon Technicum. N. 



la 



