Notices respecting New Books. 59 



torial ratios by -^-. The formula p= ~^- * —^ (p indicating 

 the ratio of the mean range to the mean height) gives — 







Theoretical 



Observed 









ratio. 



ratio. 



Latitude .. 



..0 



•002190 



■002670 



Latitude .. 



.. 78 37 



•000432 



•000404 



showing that the ratio is less near the pole and greater near the 

 equator than our theory indicates, a natural consequence of the 

 centrifugal force at the equator and the cold surface currents 

 that produce the trade-winds. 



The revolution of the sun around the great Central Sun must 

 also cause barometric fluctuations that may possibly be measured 

 by delicate instruments and long and patient observation. The 

 Torricellian column may thus become a valuable auxiliary in veri- 

 fying or rectifying our estimates of the distances and masses of 

 the principal heavenly bodies. 



VII. Notices respecting New Books. 



Manual of the Metalloids. By James Apjohn, M.D., F.R.S., 

 M.R.I. A., Professor of Chemistry in the University of Dublin. 

 London: Longmans, 1864, pp. viii and 596. 

 r PHIS work forms one of the series of Scientific Manuals issued 

 -*- under the auspices of Professors Galbraith and Haughton of 

 Trinity College, Dublin. With regard to its intended scope and aim, 

 the author says, " In preparing it my wish has been to produce a 

 condensed, but at the same time tolerably comprehensive treatise, 

 in which no topic of importance should be omitted, while all would 

 be discussed with as much brevity as is consistent with clearness. 

 It is intended as a Handbook in Chemistry for students in Medicine 

 and Engineering, . . . . " 



In books intended for the use of students, completeness in relation 

 to matters of detail is unattainable, and is not even to be desired ; 

 but it is very important that such books should be as free as possible 



from errors, and that the knowledge gained by the study of them 



though necessarily limited in extent — should be accurate, and should 

 serve as a firm foundation for further acquisitions. In such works 

 even slight mistakes often amount to serious faults ; and thev are 

 the less excusable, since the author, not being called upon to enter 

 upon the more abstruse parts of the science, may generally ensure 

 accuracy, upon the subjects of which it is desirable that he should 

 treat, by exercising a moderate degree of care. In the present 

 volume, errors in regard to the simplest matters of fact are, unfor- 

 tunately, by no means rare, nor are they all of small importance. 

 It would be tedious to the reader were we to quote all the passages 

 upon which this assertion is founded : the following must suffice as 

 specimens of many more that might be given. 



