REMARKS, &C. 327 



REMARKS 



0N T 



ARTIFICIAL HORIZONS, &c. 



By Mr. REUBEN BURROW. 



'"THE utility of a perfecl horizon, and the liablenefsof 

 A quickfilver to be difturbed by the leaft wind, have 

 induced numbers of people to invent artificial horizons 

 of different kinds, and many of them very complicated. 

 Some time ago, having occafion to determine the fitua- 

 tionof feveral places by aftronomical obfervations, and 

 there being no aftronomical quadrant belonging to the 

 Company in the fettlement, I was under a neceflity of 

 determining the latitudes by a fextant, and that at a 

 time when the fun paffed fo near the zenith as to make 

 it impoflible to get meridian altitudes : I therefore col- 

 lected all the different artificial horizons and glafs roofs, 

 and other contrivances for that purpofc, I could meet 

 with'; but, though they appeared cone6r, the refulr.s 

 were very erroneous. I examined them by # bringing 

 the two limbs of the fun. feen by direct vifion, to touch 

 apparently in the telefcope of a fextant, and thenob- 

 -ferved the reflected' images in quickfilver, which Mill 

 appeared to touch a 'e ; but, on examining the 



reflected images iri the reft of the artificial horizons, 

 none of them appeared to touch • and the error in many 

 was very considerable. I tried a number of other 

 methods with little fuccefs, as they were mofth' com- 

 binations of glaffes. At iaft, accidentally hearing ioine 

 officers fpeaking of " Tents that would neither turn 

 fun or rain," I confide red that the ravs of the fun 

 would pafs through cloth un refracted; and in confe- 



quence 



