Royal Astronomical Society. 517 



II. On an Astronomical Time Watchcase. By the Rev. Professor 

 Chevallier. 



The author has invented a contrivance, by means of which a com- 

 mon watch can, at pleasure, be made to denote sidereal time, nearly 

 enough for the purpose of warning an observer when his presence 

 will be wanted in the observatory. 



The principle of the contrivance is to set a moveable face to the 

 hands of the watch i7istead of setting the moveable hands to a fixed face. 

 This is effected by means of a circular box containing the watch. 

 The lid has a circular aperture, through which the hands of the 

 watch may be seen. Upon the lid is a circular plate, upon which is 

 engraved a double circle of hours, from to 1 2 and from 1 2 to 24 ; 

 and a concentric inner circular plate, moveable separately, upon 

 which the minutes are engraved. A small pointer projects from the 

 part of the inner circle, which indicates 60 m , directing the eye at 

 once to that point as the temporary upper part of the face. 



In order to set this watch-case for use, it is quite unimportant 

 what time the watch itself indicates. The lid is simply placed so 

 that the hour-hand of the watch may point to the part of the hour- 

 circle corresponding to the sidereal hour : the minute-circle being 

 subsequently turned, till the minute corresponding to the minute of 

 sidereal time is opposite to the minute-hand of the watch. 



The hands of the watch then, as referred to the temporary position 

 of the moveable circles, indicate sidereal time ; and, if they are set a 

 little too fast, they will continue to do so to the nearest minute for 

 almost six hours ; thus giving the observer upon his table a dupli- 

 cate of his observatory clock, sufficiently exact for the purpose which 

 he wants. 



. It is plain that this contrivance can, with the greatest ease, be ap- 

 plied to any common watch-case ; or, if a watch-glass were made 

 capable of being turned round, the hours might be marked upon the 

 glass, the minutes being engraved upon a moveable rim upon the 

 watch-case. 



III. Mean Places, for Jan. 1, 1842, of 50 Telescopic Stars, within 

 two degrees North Polar Distance, observed in the years 1842 and 

 1843, at Markree, in the County of Sligo. By E. J. Cooper, Esq. 

 and A. Graham, Esq. 



IV. On the Orbits of several ancient Comets. By J. R. Hind, 

 Esq. of the Royal Observatory, Greenwich. Communicated by the 

 Rev. R. Main. 



V. Approximate Elements of the Orbit of the Comet recently 

 discovered by M. Faye. By Professor Henderson. 



VI. Two circular letters from Professor Schumacher on the Comet 

 discovered by M. Faye. Communicated by F. Baily, Esq. 



Abstracts of the preceding four communications are given in the 

 Society's Monthly Notices, vol. vi. No. 2. 



VII. Results of Observations made with a Sextant and Pocket 

 Chronometer, for determining the Latitude and Longitude of the 

 Apartments of the Society. By J. Hartnup, Esq. Communicated 

 by Captain W. H. Smyth, R.N. 



