2o6 ASTRONOMICAL and 



again fubdivided with eafe by the eye, aided with the ml- 

 crofcope. This fextant I ufed iu taking all the lunar 

 diftances. 



Qthly. A furveying compafs made by Mr. Benjamin 

 Rittenhoufe upon the neweft, and mod approved plan. 



lothly. Two excellent Hop watches, with fecond hands, 

 to be ufed if any accident ihoiild happen to the regulator, 

 or at places to which it could not be taken. 



iithly. Two excellent cafes of drawing, and plotting 

 inftruments. 



I 2thly. Two copper lanterns to be ufed in tracing 

 meridians, and giving the diredtion of lines w-hen deter- 

 mined in the night by celeftial obfervation. Thofe lan- 

 terns had four fides, each fide about 4- inches wide, and 

 8 inches high ; in the front ot each is a Hit, or aperture 

 of about 5 inches in length, and 3 tenths of an inch in 

 breadth ; through which a lighted candle is to be ken in 

 the night. To render this flit, or aperture more coni'pi- 

 cuous in day-light, a flip of white paper was ibmetimes 

 fafliened to the copper on each llde of it, and at others 

 a piece of white paper was placed behind the lantern, 

 which rendered the aperture very diitinft, when the door 

 which is on the oppofite fide to the aperture was opened. 

 L. L. L. Plate V. are different views of the lanterns. 



I 3th!y. An apparatus to fecure the water in uhng the 

 artificial horizon againft tiie effedts of the wind : As an 

 accurate knowledge of thb time, is of the utmoft confe- 

 quencc in aftronomy, it is abfolutely neceffary that the 

 obfervations for that purpofe be made with certainty. 

 On this account 1 fliall be more particular in defcribing 

 the method I have purfued for fifteen years, without find- 

 ing it liable to any objecflion of weight. It is well known 

 that equal altitudes of the fun, or flars, afford the readieft 

 method of obtaining the time tor occafional purpofcs, and 

 at land thofe equal altitudes muft be taken from an ar- 

 Uficial horizon if a quadrant, or fextant be ufed. It is 



therefore 



