452 Analyses of Books, [Dec. 



that, as my friend Mr. Dalton has determined, the diameter of 

 these perforations must not be diminished beyond a certain 

 extent, otherwise the flame will not be so luminous as it is 

 when they arc of the ordinary size. 



After the explanations which have been given of the nature 

 of flame, it seems easy to assign a reason for the amazing 

 power of the oxyhydrogen blowpipe. In this instance, the 

 combustible body, or hydrogen, is so completely supplied with 

 the supporter of combustion or oxygen, that the flame, instead 

 of having, as in ordinary cases, only a superficial film of in- 

 flammation, is a solid mass of fire. The cause of the difl'er- 

 ence, therefore, between common flame and that of the oxy- 

 hydrogen blowpipe is evident. 



The common blowpipe may also be explained upon the same 

 principle. The power of the flame is increased by the intro- 

 duction' of a quantity of oxygen, which aftbrds a thicker cover- 

 ing of combustion. Hence the reason that the mouth blow- 

 pipe is inferior to one of common air; since the air blown 

 through it contains a less proportion of oxygen than is contained 

 in the same bulk of the atmosphere. 



I shall not lengthen this paper by adverting to any other 

 topics that may be suggested by a consideration of the prin- 

 ciple which it has been my object, on this occasion, to illus- 

 trate and confirm. 



Article X. 

 Analyses of Books. 



Philosophical Transactions of the Royal Society of London, for 

 1825. Part L 



Having already reprinted one of the papers contained in this 

 part of the Philosophical Transactions, the titles of which 

 are given below, in the Annals for August last, and offered some 

 account of the contents of four others in our reports of the 

 Proceedings of the Royal Society, but one of the remaining 

 communications, that by Mr. Christie, which begins the volume, 

 will how require to be noticed at any length. 



1. On the Effects of Temperature on the Intensity of Magnetic 

 Forces ; and on the Diurnal Variation of the Terrestrial Mag- 

 netic Intensity, By S. H. Christie, Esq. MA. of the Royal 

 Military Academy : communicated by the President. 



Mr. Christie has already distinguished himself among the 

 labourers in the rich field of philosophical research which 

 Magnetism has for some years past afforded, in consequence 

 principally of Professor Oersted's discovery of its relations to 



