December 22, 1910] 



NATURE 



235 



w hich are altogether omitted, and the Cetacea, of 

 which only a list is given. The seventy-five species 

 of mammals are dealt with in an interesting manner, 

 references being made to their habitat, food, care of 

 young, change of coat, hibernation, &c. The com- 

 mon and Latin name of each species is given, and 

 we are glad to note that where the Latin name has 

 recently been changed the older and more familiar 

 designation has also been added. The large number 

 (442) of birds in the British list necessarily means 

 that each can receive only comparatively short notice 

 in the space available ; nevertheless, a large amount 

 of interesting information is packed into the twenty 

 pages devoted to this part of the subject. The rep- 

 tiles — three snakes, the blind-worm, and two lizards — 

 rind the Amphibia, seven in number, are described, 

 with notes on their distribution and habits. The 

 account of the fishes, which is restricted to those 

 occurring in fresh water, also contains many interest- 

 ing observations on their distribution, the distinctions 

 between allied species, spawning, &c. 



.An appendix contains a full list of the species of 

 vertebrates, other than turtles and marine fishes, 

 which have been recorded from the British area. In 

 the case of those birds which have occurred not more 

 than six times notes are added or references given to 

 the records of capture. The illustrations, about half 

 of which are reproduced from photographs, are good, 

 and several are of special excellence. The volume 

 forms a thoroughly serviceable guide to the collection. 



The Sea-Kings o/ Crete. By the Rev. James Baikie- 

 Pp. xiv + 274. (London : A. and C. Black, 1910.) 

 Price ns. 6d. net. 



As a compilation this work shows great diligence ; it 

 has evidently been written con amore, and its aim is 

 most praiseworthy ; but it has no scientific value. 

 VV'e prefer to see ocuvres de vulgarisation of this kind 

 written, when possible, by the excavators themselves. 

 This is no doubt a counsel of perfection ; they have 

 usually too much to do to write popular books. But 

 in any case, such books should onlv be written by 

 trained archaeologists with a first-hand knowledge of 

 the subject and a personal acquaintance with Crete 

 itself. Of these qualifications we do not see much 

 evidence in Mr. Baikie's work, which, after the pub- 

 lication of the books of Mrs. Hawes (a Cretan excava- 

 tor) and Prof. Burrows, seems scarcely needed. 



Pinro. (Brook's patent.) (W. J. Brooks and Co., 



Letchworth, Herts.) Price 15. per twelve yards. 

 This device consists of a thin metal tape, from which 

 fine steel points project at intervals of about four inches. 

 It is intended to be used by draughtsmen as a substi- 

 tute for drawing-pins, and also for attaching canvas, 

 posters, fabrics, &c., continuously along the edges. 

 The contrivance does not seem to us likely to be gener- 

 allv adopted, but there are special circumstances under 

 which it might be found very- serviceable. 



Teachers' Notes on Nature-Study : Plants and Animals. 



Pp. viii + 232. (London: Blackie and Son, Ltd., 



n.d.) Price 15. 6d. net. 

 This re-issue of an old work will not commend itself 

 to teachers who desire to make the school study of 

 science a training in accurate observation, simple 

 reasoning, and precise expression. The method of 

 teaching, the haphazard arrangement of subjects, and 

 the general absence of scientific treatment, all remind 

 the reader of the discredited stvle of '"object-lesson" 

 common ten or fifteen years ago. The compiler, 

 whose name is withheld, does not appear to realise 

 the necessity in the case of young pupils for basing 

 every lesson on plants upon specimens in the hands of 



NO. 2147, VOL. 8sl 



each child, and encouraging the children to draw from 

 the specimen rather than from the teacher's black- 

 board sketches. 



The Scientists' Reference Book and Pocket Diary 

 for 191 1. (Manchester: J. Woolley, Sons and Co., 

 Ltd.) Price is. 6d. ; bound in morocco, 2s. 6d. 

 In addition to a handy diary in which provision is 

 made also for memoranda aiid addresses, this pub- 

 lication provides a very useful book of tables and 

 facts likely to be of use to workers in science, as well 

 as to students. In view of its small price the com- 

 bination is likely to secure a wide popularity. 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications.] 



Histoiical Note t n Recalescence. 



The interesting resume of Prof. .Arnold's British 

 •Association paper on recalescence, which appeared in 

 Nature for December i, contains the following statement 

 in the opening paragraph : — 



" In 1868 the late Dr. Geo. Gore, F.R.S., discovered the 

 recalescent points now known as Ar, and Ar„ and in 

 1872 Prof. W. F. Barrett, F.R.S., discovered the 

 recalescent point Ar,, which is now known as the carbon 

 change point. Prof. Barrett gave the phenomena the 

 generic title of ' recalescence,' by which they have been 

 known ever since." 



.As no little misapprehension exists on this subject, it is 

 desirable, as a matter of historical accuracy, to state that 

 Dr. Gore did not discover the phenomenon of recalescence, 

 but he was the first to observe the remarkable momentary 

 elongation of an iron wire during cooling from bright 

 incandescence, which important observation subsequently 

 led to the discovery of recalescence. 



Owing to the great practical importance which recales- 

 cence has assumed in the hardening and heat treatment 

 of steel, it may perhaps be of interest if I briefly state 

 the early history of this discovery'. 



The Proceedings of the Royal Society for January 28, 

 1869, contains a paper by Dr. Gore which records the 

 anomalous behaviour of cooling iron above referred to — 

 its sudden transient expansion at a dull red heat. This 

 anomalous behaviour Dr. Gore found was not shared by 

 other metals, and he states that no reverse effect was 

 noticed upon heating iron wire to incandescence.^ 



Some two years later, having to deliver a lecture before 

 the Royal Dublin Society on the " Molecular Changes that 

 accompany the .Act of Magnetisation," I was anxious to 

 show Mr. Gore's interesting discover}", as it appeared 

 likely to be connected with the resumption of the mag- 

 netic state in iron when cooling from a white heat. In 

 answer to my inquiry Mr. Gore kindly furnished me with 

 his apparatus, and as he said he had no further use for 

 it I purchased it from him, and it is still in my possession. 

 To make the effect visible to a large audience a mirror 

 was attached to the spindle which moved the index, and 

 from it a ray of light was reflected to a distant scale. 

 This device revealed the fact, overlooked by Dr. Gore, that 

 a small momentary contraction of the iron wire took place 

 during its heating to incandescence, approximately at the 

 same temperature at which the momentary elongation 

 occurred in cooling.^ 



Dr. Gore having informed me, in a letter dated May, 

 1872, that he was not pursuing his original observation 

 and that the subject was quite open to anyone. I felt at 

 liberty to continue the inquiry-. .Accordingly, the follow- 

 ing year. Dr. Guthrie having kindly placed his laboratory 



J 'n fact some eighteen months after his original oh-ervation Dr. Gore 

 states -n a r>ar>er published in the Phi/. Mag. for ."September, i'»7o(tbe italics 

 are his): — " The iron during; cooling . . . suddenly elongated bv diminution 

 of cohesion ... a rorresponding hut reverse phenomenon did not occur 

 diirine the process o^ heating the wire." 



2 This lecture was repeated at thf London Tnst"lution a year later, and a 

 full report of it is published in the Journal of that Institution. 



