45+ Expansive Force of Steam. 



Dr. Ure's numbers are uniformly higher tlian those which 

 I have given ; and as he laid them down by experiment, I sus- 

 pect that our mode of operating must have differed. 



I shall not at present enter upon the question, vphether it is 

 more oeconomical to obtain power by heating- water to a high 

 temperature, or a comparatively low one ; for although the an- 

 nexed Table shows that 38 degrees of heat only produce a force 

 equal to one atmosphere, while about 12 degrees of heat will 

 give the force of the 5th atmosphere ; still this fact alone would 

 not prove the ceconomy of high-pressure steam. — To settle this 

 question, it is necessary to ascertain what relative proportions 

 oi'fucl must be consumed to produce each degree of force. 



From experiments made on a large scale, I have long been 

 convinced of the value and ceconomy of high-pressure steam, — 

 and this conviction led me to give the opinion which I stated be- 

 fore a Committee of the House of Commons some years since*. 



Many important improvements have resulted from the use 

 of this valuable agent since that period ; and others, which will 

 arise from our more perfect acquaintance with its properties, 

 will lead us to rejoice that the Legislature did not limit its use 

 in consequence of a few injudicious applications of it. 



I am at this time engaged in experiments to ascertain at 

 what expense of fuel each degree of force can be obtained; and 

 I have reason to think that the apparatus which I have con- 

 structed will give me results on which I may rely. 

 1 am, Gentlemen, yours truly, 



Philip Tayloe. 



P. S. I observe that the engraved plate varies a little from 

 the original, owing to the shrinking of the paper on drying; — 

 but as this effect is equal, it does not interfere with its compa- 

 rative accuracy. 



XCIV. Notices respecting Neiv Booh. 



Conversations on Mineralogy: with Plates engraved by Mr. and 



Miss Lowry, from Original Drawings. 2 vols. 12mo. 



1 HIS work, though its pretensions are modest and unassum- 

 ing, will be found highly useful, and well adapted to answer 

 the purpose for which it is intended, namely, as stated by 

 Miss Lowry in her preface, for it is to Uiis lady that we are 

 indebted for the publication, " to prepare the young minera- 

 logist for the study of more learned treatises." 



The conversational method of imparting knowledge ap- 

 pears to be well adapted for elementary books, as the diffi- 

 culties most likely to occur to a beginner are stated and an- 



# Pliil. Mag. Vol. L. p. \m. 



swcrcd, 



