834 M. Prevost on the Gtneration of Animals. 



A number of other small stars, which are spoken of as diffi- 

 cult to observe from their minuteness, are seen more or less 

 distinctly with this instrument. 



Amongst the closer and larger stars I have tried the tele- 

 scope upon those commonly selected as tests, viz. 



Castor, which is distinctly double with 120, and well open- 

 ed, and stars perfectly round, with 360 and 700. 



y Leonis and a Piscium are seen, with the same powers, 

 equally round and distinct. 



In s Bootis the small star is well separated from the larger, 

 and its blue colour well marked with a power of 360. 



ri Coronae Borealis is seen double with a power of 360 and 

 700. 62 Orionis, ^ Orionis, and others of the same class, are 

 also well defined with the same powers. 



Still, however, it must be admitted that the telescope is not 

 so competent to the opening of the close stars, as it is power- 

 ful in bringing to light the more minute luminous points. 



Of the planets, I have only had an opportunity of trying the 

 telescope on Venus, Saturn, and Mars ; and the latter is too 

 low to furnish a good test. Venus is beautifully white and 

 well defined with a power of 120, but shows some colour with 

 360. Saturn, with the 120 power, is a very brilliant object, 

 the double ring and belts being well and satisfactorily defined, 

 and with the 360 power it is still very fine. The moon also 

 is remarkably beautiful, the edges and the shadows being well 

 marked, while the quantity of light is such as to bring to view 

 every minute distinction of figure and shade. 



AiiT. XI K. — On the Mode of Generation in the Mya Pic- 

 tor um — in the Helix palustr is — and in the Muhis gobio ; and 

 Notice on the Circulation of the Foetus in Ruminating Ani- 

 mals. By M. Prevost of Geneva. * 



M. Prevost, along with M. Dumas, has been engaged for 



• De la Generation chez les Monies dex Peinlres. Read at the Physical 

 and Natural History Society of Geneva, March 17, 1825. — De la Genera- 

 tion chez le Lymnee. Read at the same Society in 1826. — De la Genera- 

 tion chez le Sechot. Read at the Physical Society of Geneva, 1825. — Note 

 sur la Circulation du Foetus chez les Ruminants. Geneva, 1828. 



