378 Notices respecting New Booh. 



Professor Whewell has very recently proposed* to ascei*- 

 tain the height of the clouds or of a mountain by means of 

 the formula 



sin {cc-'pY 

 in which 



H is the height of the cloud above a horizontal mirror, 



// the vertical height of the observer above this mirror, 



« the angle of depression of the image of any point of the 



cloud below the horizontal plane passing by the eye of the 



observer, 

 |3 the angle of elevation of the same point above this plane. 



It is evident that this formula is identical with thatf which 

 I published four j'ears ago, and which has been reproduced in 

 the scientific journals of Germany. The learned Master of 

 Trinity forgot that at the time when he made his commu- 

 nication to the Section of Physics of the British Association 

 at Southampton, I informed him that what he proposed as 

 new was already in print. 



LI. Notices respecting New Books. 



liesidls of Astronomical Observadons made during the years 1834, 

 183.5, 1836, 1837, 1838, at tlie Cape of Good Hope; being the 

 Comptetion of a Telescopic Survey of the whole Surface of tlie visible 

 Heavens, commenced in 1825. By Sir John F. W. Herschel, 

 Bart., K.H., tSc. 8^c. London: Smith, Elder and Co. 1847. 



A S many of our readers may not have had an opportunity of 

 -^^ perusing the exceedingly important and interesting volume 

 recently published under the above title, we propose to make a few 

 extracts from it for the purpose of giving them an idea of its prin- 

 cipal contents. Where it may appear desirable (having regard to 

 our narrow limits) to condense or abridge, we shall make it a rule to 

 adhere as closely as may be to the language of the author. 



In his Introduction, the author states that the present work com- 

 pletes a review of the sidereal heavens which he commenced in 1825, 

 with the object of re-examining the nebulre and clusters of stars dis- 

 covered by Sir William Herschel in his Sweeps of the Heavens, and 

 described in three catalogues published in the Philosophical Trans- 

 actions for 178G, 1789 and 1802. The result of the re-examination 

 was given in a paper printed in the Phil. Trans, for 1833, in the 

 form of a catalogue arranged in the order of right ascension, and 



* Reports of the British Association for 1846; Transactions of the 

 Sections, p. 15. 

 t Ibid. 



