“The employment of writing down my observations, when my brother uses the 20 feet reflector, does not often allow me time to look at the heavens; but as he is now on a visit to Germany, I have taken the opportunity to _sweep_, in his absence, in the neighbourhood of the sun, in search of comets. And last night, the 1st of August, about ten o’clock, I found an object resembling in colour and brightness the twenty-seventh nebula of the _Connoissance des Temps_, with the difference, however, of being round. I suspect it to be a comet; but a haziness coming on, it was not possible entirely to satisfy myself as to its motion till this evening. I made several drawings of the stars in the field of view with it, and have inclosed a copy of them, with my observations annexed, that you may compare them together. “August 1, 1786, 9h. 50′. The object in the centre is like a star out of focus, while the rest are perfectly distinct, and I suspect it to be a comet. Tab. 1., fig. 1. “10h. 33′, fig. 2. The suspected comet makes now a perfect isosceles triangle with the two stars, A and B. “11h. 8′. I think the situation of the comet is now as in fig. 3; but it is so hazy that I cannot sufficiently see the small star to be assured of the motion. “By the naked eye the comet is between the 54th and 53rd Ursæ Majoris, and the 14th, 15th, and 16th Comæ Berenices, and makes an obtuse triangle with them, the vertex of which is turned towards the south. “August 2, 10h. 9′. The comet is now, with respect to the stars A and B, situated as in fig. 4. Therefore the motion since last night is evident. “10h. 30′. Another considerable star, C, may be taken into the field with it, by placing A in the centre; when the comet and the other star will both appear in the circumference, as in fig. 5. “These observations were made with a Newtonian sweeper of 27 inches focal length, and power of about 20. The field of view is 2° 12′. I cannot find the stars A and C in any catalogue, but I suppose they may easily be traced in the heavens; whence the situation of the comet, as it was last night at 10h. 33′, may be pretty nearly ascertained. “You will do me the favour of communicating these observations to my brother’s astronomical friends. “I have the honour to be, etc., “CAROLINE HERSCHEL. “SLOUGH, NEAR WINDSOR, _August 2, 1786_.” Many also of the nebulæ contained in Sir W. Herschel’s catalogues were detected by her. Indeed the unconquerable industry of the sister challenges our admiration quite as much as the intellectual power of the brother. _WORKS ON ASTRONOMY._