1 68 



NATURE 



[October 14, 19 15 



with their favourable and unfavourable charac- 

 teristics, methods of preparing and mixing" the 

 ingredients (including some brief historical 

 notices), the process of pressing, and the final 

 process of hardening. The subjects of cost, of 

 manufacture, and defects are dealt with in special 

 chapters, as are also the physical properties of 

 the products. The work is embellished with 

 numerous illustrations depicting machinery and 

 appliances suitable for properly carrying out the 

 diiferent kinds of operations. 



Much of what is contained in the volume is 

 based partly on the author's personal experiences, 

 and partly on such experiences of other people 

 as have come under his notice. This is in itself 

 a highly commendable feature, but the author's 

 confidently expressed opinions, assuming them to 

 be well-founded, would lose none of their weight 

 if the experimental data on which they are based 

 were set forth more frequently than is the case. 



There are a number of misprints, some of them 

 trivial, but several may give rise to much doubt 

 and perplexity. Apart from mere misprints, 

 there are some loosely worded statements which 

 would scarcely be expected from such an experi- 

 enced writer as Mr. Searle appears to be, judging 

 from the number of his published works. Thus, 

 near the bottom of page 26, we are told that 

 "the three essential ingredients — aggregate, lime, 

 and water — must be: (i) Ground to the requisite 

 fineness and graded (if necessary). (2) The proper 

 proportion of each must be weighed or 

 measured. (3) Mixed to form a homogeneous 

 mass in which the lime is fully hydrated." The 

 italics here are, of course, not the author's. 

 Comment is scarcely necessary. It is not sug- 

 gested that the meaning is obscure, but in quasi- 

 scientific works on technical subjects there should 

 be no flagrant flouting of grammatical rules. On 

 page 82, line i8, 7 per cent, is mentioned instead 

 of 07 per cent. There seems no valid reason for 

 the spelling, in some of the later chapters, of 

 " absorbtion " instead of the more orthodox " ab- 

 sorption." A curious mistake occurs at the 

 bottom of the table on page 120, where the "cost 

 of manufacture " of "cement-sand bricks" is 

 stated to be "i month." In the last sentence 

 of the second paragraph on page 10, owing pre- 

 sumably to displacement of a comma, an absurd 

 statement is made. It is true that the real mean- 

 ing is rendered clear in the following paragraph, 

 but a practised writer ought surely to guard 

 against such slips. 



The present writer has arrived at the conclusion 



that the author is less assailable as regards his 



treatment of the practical aspects of his subject 



than when dealing with more speculative ques- 



NO. 2398, VOL. 96] 



tions. • Thus, after giving in a tentative way the 

 results of an analysis of the cementing material 

 in non-plastic bricks, and suggesting a formula 

 to correspond, he proceeds to apply this formula 



in a chemical equation to explain the reaction by -j 



which such cementing material is formed. The 3 



statement which accompanies it may constitute a j 



fairly accurate general account of what takes \ 



place; but although more than one "if" is ex- j 



pressed or implied in the explanatory sentence, ] 



the equation somehow seems to suggest a more t 



intimate knowledge of this particular reaction J 



than is justified by the actual facts, as the author 1 



himself distinctly states more than once that the I 



composition of the binding material is not de- i 



finitely known. Again, in criticising the results j 



of experimental work of F. F. Wright, performed ; 



at the Carnegie Institute, Mr. Searle goes so far ; 



as to assert that "if F. F. Wright had worked : 



on a large scale and with better facilities, he would I 



probably have realised that his experiments afford : 



a much stronger confirmation of the composition ^ 



suggested by the author of the present volume I 



than they do of the existence of a zeolite, as the 5 



latter, so far as is known, do not possess cemen- j 



titious properties." This may seem convincing z 



to the author, but to a trained mind the conclusion ; 



is very far from being established, even when .j 



taking into account the experimental evidence by I 



which he plausibly claims to prove the general ^ 



accuracy of his conclusion. ^ 



With some reservation as regards certain of ; 



the matters to which attention has been directed, 'i 



the work should prove useful for the objects the '■ 



author had in minji when preparing it. One ex- 5 



cellent feature worthy of mention is the com- ■ 



parison table occasionally introduced, showing in '^ 



one view a number of more or less different pro- j 



cesses, or the properties of a variety of different '^ 



products, etc. There is also a serviceable index. ■ 



J. A. A. J 



THE PANAMA CANAL. 



The Panama Canal: Comprising its History and ; 



Construction, and its Relation to the Navy, ■, 



International Law, and Commerce. By R. E. * 



Bakenhus, Capt. H. S. Knapp, and Dr. E. R. "( 



Johnson. Pp. xi + 257. (New York: John ,| 



Wiley and Sons ; London : Chapman and Hall, j 



Ltd., 191 5.) Price 105. 6d. net. '; 



I'^HIS book has a claim to authority. It con- ,; 



sists essentially of a series of papers which "; 



were originally published in the Proceedings of , 



the United States Naval Institute. Of the three * 



authors the first, Mr. Bakenhus, is a member of : 



the Corps of Civil Engineers of the United States )! 



Navy, the second, Capt. H. S. Knapp, U.S.N., \ 



