Notices respecting New Books. 425 



and lastly transition compounds to the benzene series. Under the 

 second class we have first of all an excellent summary of the differ- 

 ences between the two great classes, some sixteen pages being 

 devoted to the general theory of the constitution of benzene and 

 its derivatives. Then follow the groups of hydrocarbons, haloed 

 derivatives, nitro-derivatives, amido-derivatives, azo- and diazo- 

 compounds, sulphonic acids, phenols, alcohols, aldehydes, and 

 ketones, acids, indigo group, diphenyl group, diphenylmethane 

 group, triphenylmethane group, dibenzyl group, naphthalene, an- 

 thracene, and phenanthrene, pyridine and quinoline groups, terpenes 

 and camphors, resins, glucosides, albuminous substances, &c. 



The translator has done his part of the work well, although we 

 detect distinct Teutonisms here and there. The proofs have had 

 the advantage of being revised by the author. "We can confidently 

 recommend the work to both teachers and students, and we hope that 

 in a future edition the translator will have an opportunity of modi- 

 fying the nomenclature in certain cases so as to bring it more 

 into harmony with that adopted in this country. 



An Elementary Treatise of Mechanics, for the use of Schools and 



Students in Universities. By the Eev. Isaac Warren, M.A. 



(London : Longmans, 1889. Pp. 144.) 

 It may be in the recollection of some of our readers that in our 

 issue for January 1887 the Eev. T. K. Abbott raised the ques- 

 tion, " To what order of Lever does the Oar belong ? " and proposed 

 to show that " the vulgar conception of the oar as a lever of the 

 first order is correct." Our author, in a note, after stating that 

 the oar is commonly regarded by writers on Mechanics as a lever of 

 the second kind, proposes to reconcile these apparently conflicting 

 statements. We use the summary he himself gives of the results 

 he arrives at, viz. : — (1) The oar must be regarded as a lever of the 

 second order if the resistance acting at the rowlock be understood 

 to include, not only the external resistance to the boat's motion, 

 due to the action of the fluid in which the boat floats, but also the 

 reaction engendered by the person of the oarsman when he pulls the 

 oar. (2) If we consider only the resistance offered by the fluid to 

 the boat's motion, it will be found that this resistance is related to 

 the effort employed by the rower at the handle of the oar in exactly 

 the same ivay as if this resistance acted at the blade of the oar, and as 

 if the rowlock were the fulcrum, i. e. practically as if the oar were 

 a lever of the first order. The author's work will be found on pages 

 129, 130, and he concludes thus: — "Whether this result might 

 have been a priori predicted from the circumstance that the row- 

 lock is a fixed point relatively to the rower, the author leaves for. 

 others to determine." The text forms a handy book for junior 

 students, and is accompanied by full store of illustrative exercises, 

 with several specimen (Trinity College, Dublin) papers. 



It should be mentioned that the present is the first part of the 

 complete treatise, and is concerned (in the text) with Statics only. 



Phil, Mag. S. 5. Vol. 28. No. 174. Nov. 1889. 2 I 



