May 25, 191 1] 



NATURE 



409 



Such a book undoubtedly raises the question 

 whether it is advisable in the interests of the students 

 to lay before them only fragments of a complete 

 science, even though it be admitted that the par- 

 ticular fragments that are most likely to be useful 

 to them in their after-career have been selected with 

 care and discrimination. On one hand, it may be 

 urged that it is better for the coal-miner to have a 

 rudimentary knowledge of chemistry than to have 

 none at all, and that unless the amount of science 

 required of him is cut down to the lowest possible 

 limits, he will have none of it, whilst on the 

 other we have the obvious dangers that attend 

 a limited knowledge of any subject, and in the pre- 

 sent case more especially the risk that the man who 

 has mastered such a book as Prof. O'Shea's will think 

 that he has got a real grasp, of the science of chem- 

 istry and w-ill remain in ignorance of the vast field 

 that this book does not profess even to touch upon. 

 Xo chemist needs to be told that a book that treats only 

 • f the chemistry of certain of the metalloids must 

 necessarily present only a very imperfect outline of the 

 principles of modern chemical science, and there 

 would probably be a pretty general consensus of 

 opinion that, if possible, it would be far better for 

 the mining student to learn the elements of chemistry 

 as an abstract pure science from a book on chemistry, 

 and, having mastered these, then to be taught what 

 portions of that science he has to apply to the problem 

 of his daily work. 



Prof. O'Shea has evidently come to the conclusion 

 that the latter method is the less practical, and no 

 doubt there is very much to be said for his view ; it 

 must be admitted that the coal-miner who thoroughly 

 masters his little book will benefit greatly thereby, 

 and will certainly obtain a fairly clear understanding 

 of many of the phenomena that he meets with in the 

 pit. The first chapters give an outline of the leading 

 principles of chemical combination, and of the physical 

 and chemical properties of oxygen, nitrogen, air, 

 hydrogen, water, sulphur, carbon, and the oxides 

 of carbon, including a useful chapter on flame and 

 the safety lamp ; then follow a number of chapters 

 on the application of the facts thus set forth, on coal, 

 coking, and the recovery of by-products, on explosives, 

 and on gas and dust explosions ; the book concludes 

 with some brief chapters on certain chemical and 

 physical calculations, which will prove useful for the 

 proper understanding of certain parts of the subject. 

 Prof. O'Shea has done his work well, and has 

 evidently selected his material with great care and 

 judgment, and with a sound appreciation of the needs 

 .ind limitations of the coal-miner. He has also taken 

 care to express himself throughout in plain, simple 

 language, and it may be suspected that it is to the 

 desire for simplicity that a certain amount of slip- 

 shod writing in the book is due, as, for example, in 

 such expressions as "one of the most improved 

 forms," "a purely dust explosion," &c. ; a somewhat 

 flagrant case is the definition of the atomic weight 

 of an element as " a number which represents how 

 much heavier its atom is than the atom of hydrogen," 

 where the author obviously means "how* many times 

 as heavy.*' 



NO. 2169, VOL. 86] 



It is difficult to see why Prof. O'Shea should insist 

 that nitro-glycerol is the more correct name for nitro- 

 glvcerine ; the latter is a thoroughly well-known and 

 generallv accepted trivial name, and if he wants 

 chemical exactitude, he should have used the strictly 

 correct form, glyceryl tri-nitrate; it is now generally 

 recognised that nitro-glycerine and gun-cotton are not, 

 as Prof. O'Shea states, nitro-compounds, but nitrates. 

 In the same way exception may well be taken to the 

 statement that coal occurs in "veins." Such in- 

 accuracies, though they are undoubtedly blemishes in 

 an otherwise very well-written book, do not, of course, 

 detract seriously from its value as a whole, and will 

 presumably be corrected in a future edition. Prof. 

 O'Shea may fairly be congratulated on having pro- 

 duced a little book that gives, within a convenient 

 compass, a great deal of information that will prove 

 extremely useful to all coal-miners, and be found to 

 render very great assistance to the class for which it 

 is more particularly intended. H. L. 



ANOTHER BOOK ON EVOLUTION. 

 Phases of Evolution and Heredity. By Dr. David 

 Berry Hart. Pp. xi + 259. (London: Rebman, 

 Ltd., 1910.) Price 55. net. 



THIS book is not written by a man red-handed 

 fresh from an encounter with nature. If his 

 hands needed washing before he wrote, it was to 

 remove the dust of books. Would that the water 

 could have removed the taint of much reading also. 

 The notion that the truth must be sought in books 

 is still widely prevalent, and the present dearth of 

 illiterate men constitutes a serious menace to the 

 advancement of knowledge. 



The author of this book constitutes an exception 

 to the law that the more certain a man is that he is 

 right the more probable is it that he is wrong. Dr. 

 Hart lays stress on the fallibility of the human intelli- 

 gence. He realises that he may be mistaken. And 

 he is. The title-page of his book bear these words : 



" Every seeker after Truth is dependent on the 

 knowledge of his Age. He must, therefore, shape his 

 coat according to his cloth, and expect a misfit. 

 The words of Cromwell to the General Assembly of 

 the Scottish Church should ever ring in his ears : ' I 

 beseech you, in the bowels of Christ, think it pos- 

 sible you may be mistaken.'" 



The book deals with "Mendelism," "Biometry," 

 "Mnemism," "Observation Bee-Hives," "Evolution 

 in Religion," and "Men who have Revealed Them- 

 selves." 



The obstacles which, according to Dr. Hart stand 

 in the way of our acceptance of the Mendelian hypo- 

 thesis seem to us wholly illusory. He does not see 

 why segregation should not occur in F,, and asks 

 the following questions, which seem to us quite easy 

 to answer. " i. Why, if this explanation be true, do we 

 get all the plants of the F, tall-dwarf crossing, tall, 

 and not tails and dwarfs in the 1:2:1 ratio?" 

 \Atmver: Because the only one kind of union between 

 gametes can take place, namely tallxdwarf.) "2. 

 The recessive quality reappears in F^. Is it not, then, 

 equal to the dominant? " [Answer: Yes, if you like.] 



