December i, 19 io] 



NATURE 



^Z7 



name, family, situation in the garden, country of 

 origin, and date of introduction; interleaved blank 

 pages are provided for notes and additions. The 

 author is to be complimented on the accuracy of his 

 work. 



Ihe Essentials of Histologv, Descriptive and Prac- 

 tical, for the Use of Students. By Prof. E. A. 

 Schafer, F.R.S. Eighth edition. Pp. xi + 571. 

 (London : Longsmans, Green and Co., 1910.) Price 

 105. 6d. net. 

 When Prof. Schafer's " Essentials " made its first 

 appearance some years ago it was at once recognised 

 that here was the book which had long been wanted, 

 and it has since then continued to occupy the foremost 

 place in the estimation of both teachers and students. 

 Every successive edition has kept the work fuUv up 

 to date in regard to practical methods, descriptive 

 letterpress, and last, but not least, illustrations. Any 

 extended notice of such a well-known text-book is 

 quite unnecessarv; all one need say of the eighth 

 edition is that it fully maintains the high standard 

 of previous editions, and the author is to be con- 

 gratulated on the continued and 

 well-deserved popularitv which it has 

 obtained. ' \V. D. H. 



The Charm of the Road. England 



and Wales. By James J. Hissev. 



Pp. xviii + 426.' (London: Ma'c- 



millan and Co., Ltd., 1910.) 



Price 10s. net. 

 Ix his latest book, Mr. Hissey is as 

 successful as ever in painting the 

 charms of travel in one's own coun- 

 tr)'. The journey described in the 

 present volume was begun without 

 a premeditated plan ; the author 

 says : — " To us the destination was 

 a trivial detail, left to settle itself 

 each day; the joy of the journey 

 was the thing, therein our pleasure 

 lay." Certainly Mr. Hissey's gos- 

 sipy description of the places and 

 scenes they met with, and the quaint 

 experiences they were fortunate 

 enough to have, is more than 

 sufficient to convince the reader 

 that the fortunate possessor of a motor-car, a pleasant 

 companion, and plenty of leisure, can have an excel- 

 lent holiday indeed in straving from one shire to 

 another, as fancy dictates. 



The excellent photographs which illustrate this in- 

 teresting travel book are good testimonv to Mr. 

 Hissey's keen eve for the beautiful and picturesque. 



likely to be uncertain, except when very close to a berg, 

 it was some time before I could arrange for the necessary 

 trials. 



In the meantime I had devised a practical form of 

 electrical microthermometer, which was given a thorough' 

 test on board the Canadian Government ice-breakers 

 during the experiments made last winter to keep the river 

 clear of ice above Quebec. So sensitive and precise did 

 this instrument prove, that a uniform temperature gradient 

 in the water of one-tenth of a degree per mile could be 

 determined from the ship, approaching an ice field from 

 open water, to an accuracy of a thousandth of a degree. 



The interesting experiments of Prof. Otto Pettersson on 

 the influence of ice on oceanic circulation, described in the 

 Geographical Journal for 1904 and 1907, made it appear 

 highly probable that the experiments I wished to try would 

 prove successful. Dr. Pettersson showed that ice melt- 

 ing in salt water produced two cold currents, one of fresh 

 water which flowed out on all sides over the surface of the 

 sea, and one of salt water which sank down by the 

 ordinary laws of convection. .'\ third current of warmer 

 sea water flowed in towards the ice, under the surface, and 

 produced the melting of the ice. 



Through the kindness of the Hon. L. P. Brodeur, 

 Canadian Minister of Marine, passage was secured on the 



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 

 rrmnuscripts intended for this or any other part of Nature. 

 ^o notice is taken of anonymous communications.] 



Marine Microthermograms and the Influence of Ice- 

 bergs on the Temperature of the Sea. 

 *u^"f application of precise temperature measurements to 

 the determmation of the formation and disintegration of 

 ice m the St. Lawrence River suggested to me the possi- 

 bility of usmg very delicate electrical thermometers on 

 stiipboard to determine the proximitv of icebergs On 

 account of the difiicult>- of the experiments, and the fact 

 Ttiat well-known authorities on navigation (including Lord 

 J^elvin) had reported that temperature measurements were 

 NO. 2144, VOL. 85] 



Fig. I. — Temperature Gradient near an Iceberg. 



C.G.S. Stanley for the trip to Hudsons Bay last July. 

 As other duties prevented me from being absent from 

 Montreal for so long a time, I was fortunate in being 

 able to send Mr. L. V. King, who had so ably assisted 

 me during the previous winter in ice studies, and who had 

 gained great facility in using the microthermometer. 



In addition to the ordinary- wire bridge which we used 

 in our river experiments, having a scale nearly 2 feet 

 long for one degree, we adapted a Callendar recording 

 mechanism to our needs, which gave us a scale of 1° C, 

 equal to 8 inches. The automatic recorder could be 

 switched on to the microthermometer at any time, and 

 records accurate to one-hundredth of a degree obtained at 

 any part of the temperature scale. They were obtained 

 while the ship steamed at full speed through heavy seas, 

 and were unaff^ected by the motion. 



I venture to show tw^o diagrams from the many Mr. 

 King obtained, which illustrate the disturbing effect of ice 

 on the temperature of the sea in summer. Fig. i shows 

 the temperature gradient approaching and receding from 

 a large iceberg passed within a half-mile from the ship in 

 the open sea off the Labrador coast. The ship's course 

 is shown relative to the iceberg. Fig. 2 shows a micro- 

 thermogram of sea temperature traced directly from the 

 charts. The proximity of ice is at once shown by a 

 movement of the pen of the recorder off the scale, to 

 return again to approximately the same position after the 



