1313.] Analyses of Books. 457 



greatest splendour, but in about three minutes it entirely disap- 

 peared. 



In the north the Aurora Borealis vvas faintly playing, from 

 which to the south the heavens (except the cloud before alluded 

 to, and a cloudy horizon) were clear, and had the appearance of 

 frosty weather. The wind at the time was easterly and much 

 r.iin had fallen during the day. 



I am of opinion that this phenomenon could not be caused by 

 the above-mentioned cloud concentrating the rays of the rising 

 moon ; for if it had, it could not have caused it either to extend 

 across the whole hemisphere, nor to have had that density which 

 this possessed : and at the same time I may remark, that the 

 moon vvas not the centre ; but, on referring to a celestial globe, 

 will be found to have been to the north of it; consequently, if 

 the moon had caused this luminous appearance, it would have 

 been in a different direction ; besides, the stream of light was 

 not in a right line, but rather bearded to the north. 

 I am, with much respect, Sir, 



Your most obedient humble servant, 



RoftKKT RENNEY. 



Article X. 

 Analyses of Books. 



A short Account of Experiments and Instruments depending on 

 the Relation of Air to Heat and Moisture, Svo. By John 

 Leslie, F. R. S. E. Professor of Mathematics in the University 

 of Edinburgh. 



Mr. Leslie has already gained considerable reputation by his 

 curious experiments on the effect of surface on the rate of cooling 

 or heating, which he published about nine years ago. In the 

 present little tract he gives us his opinions respecting the nature 

 and effects of heat in general ; and makes us acquainted with 

 some important facts which he has ascertained respecting evapo- 

 ration, the dryness and moisture of air, and the mode of pro- 

 ducing cold by evaporation. He describes a variety of inslru 

 ments which he has contrived for this kind of investigation. The 

 boob is written with considerable perspicuity ; and, as far as I 

 em judge, the style is greatly preferable to that of Mr. Leslie's 

 other literary productions. No great attention has been paid to 

 accuracy of arrangement ; and Mr. Leslie introduces without 

 ceremony (as has always been his habit) any topic which strikes 

 his fancy, whether it bears upon the subject in hand or not. 

 Perhaps the subjects trotted oi in this work are of so unconnected 



