July I, 1875] 



NATURE 



165 



and to discuss those by themselves, and the result has 

 been the most interesting and important discovery of the 

 law of storms. And if it be asked what right meteoro- 

 legists had to separate a body of disturbed observations, 

 the reply will obviously be that they are justified by their 

 success. Deny the right, and a cyclone becomes an 

 altogether false and illegitimate scientific conception. 



Now, a large and increasing number of magneticians 

 are of opinion that the phenomena of terrestrial mag- 

 netism can bear a similar treatment. They believe that 

 the sun has a daily and yearly influence on the magnetism 

 of the earth just as it has upon its meteorology, and they 

 also believe that it is the cause— the indirect cause, it 

 may be— of an abnormal magnetic influence, just as in 

 meteorology it is the indirect cause of the cyclone. 

 Some even go so far as to say that these two abnormal 

 influences, the one in magnetism, the other in meteoro- 

 logy, are intimately, connected together. This assertion, 

 however, is not now the point in question. The point is 

 that we have in magnetism certain abnormal distur- 

 bances which may be compared to abnormal meteoro- 

 logical disturbances. Now, it is held by Sir E. Sabine 

 and those who share his views, that it is expedient to 

 separate out these disturbed magnetical observations, just 

 as we] separate out the meteorology of a cyclone. This 

 school assert'that we may thus arrive at a series of pheno- 

 mena obeying very different laws from those of the un- 

 disturbed observations, and that we are therefore justified 

 in making the separation, inasmuch as we are thereby 

 led to a clearer knowledge of the various ways in which 

 the sun affects the magnetism of the earth. And they 

 insist very strongly upon the point that both these mag- 

 netic actions of the sun have diurnal and annual varia- 

 tions different from one another, so that if treated to- 

 gether we obtain a result much more complex than if they 

 be treated separately. 



We have little doubt of the policy of this method of 

 treatment, and we cannot, therefore, but regard it as a 

 misfortune that Mr. Broun has not unmistakably adopted 

 it. He has, however, given us all the individual obser- 

 vations, so that, if it be thought desirable, those magne- 

 ticians who advocate a somewhat different method of 

 reduction may make it for themselves. We need only add, 

 in conclusion, that the appendices will be found to be 

 very interesting reading, and that all who are interested 

 in terrestrial physics must look with great interest to that 

 magnificent series of researches of which the volume 

 before us forms the first instalment. B. Stewart 



OUR BOOK SHELF 



Chapters on Sound, for Beginners. By C. A. Martineau. 

 (London : The Sunday School Association ; Man- 

 chester : Johnson and Rawson, 1875.) 



We have read this little book with great pleasure. Its 

 object, the author tells us, is to teach a few of the simpler 

 facts in acoustics in such a way that the learner shall not 

 be deterred by unnecessary difficulties, either in the use 

 of technical language or in having to provide expensive 

 apparatus. Most successfully has the author attained the 

 end he had in view. It is just what a child's book on 

 science should be. Written in a simple attractive man- 

 ner, without any silly childishness, it conveys a great deal 

 of ir.foimation, and that in the best kind of way. For 

 the learner, by a series of simple experiments, is made to 



lay firmly the groundwork of his knowledge on this sub- 

 ject. All the apparatus the author requires is a toy fiddle, 

 one or two small tuning-forks, a couple of finger-glasses, 

 a clamp, a square and a round piece of glass, a gimlet, a 

 tall jar, silk thread, and some solitaire balls. With such 

 homely instruments really go»d elementary teaching is 

 given. The chapter on strings made to vibrate in 

 time with tuning-forks is capitally done, and will give 

 the learner more knowledge than he could gain from 

 many a pretentious text-book. We should like to suggest 

 to the author a few additions to his simple experiments, 

 but in the limits of this notice we cannot do more than 

 direct his attention to the Instructions in practical physics 

 given to the science teachers at South Kensington, and 

 printed for their use by the Science and Art Department. 

 There is of course nothing new in the way of experi- 

 mental illustration in these chapters on sound ; it is the 

 good use the author has. made of what has been done by 

 others that is the merit of this little book. We gladly 

 recommend it to all girls and boys who will honestly go 

 through what is to be done as well as what is to be read. 



LETTERS TO THE EDITOR 

 [The Editor does not hold himself responsible Jor opinions expressed 

 by his correspondents. Neither can he undertake to return, 

 or to correspond with the -writers of, rejected manuscripts, 

 No notice is taken of anonymous communications.'^ 



On the Temperature of the Human Body during 

 Mountain Climbing 



The account of Dr. Ford's laborious and carefully conducted 

 observations on the temperature of the body during mountain 

 climbing, given in Nature, vol. xii. p. 132, has recalled to mind 

 the results of a few observations which I made shortly after the 

 publication of Dr. Lortel's and Dr. Marcet's experiments. As 

 my results are in the main confirmatory of those of Dr. Forel, 

 they may not be without interest as a contriliution to what, 

 until the appearance of Dr. Forel's memoirs, was regarded as 

 the heterodox side of the question. 



Before joining the parly of observers sent out to Sicily to see 

 the solar eclipse of 1870, I provided myself with a set of delicate 

 clinical thermometers with a view of repeating the observations 

 of Drs. Marcet and Lortet, should any opportunity occur of 

 getting up Etna during our stay in the island. On Christmas- 

 day a number of us attempted to make our way up the moun- 

 tain, and with the aid of Mr. Fryer I made a number of obser- 

 vations of body-temperature on myself during the ascent. The 

 temperature of the mouth was taken, as in the observations of 

 Marcet and Lortet. The thermometer employed was carefully 

 selected so as to get the maximum amount of displacement in 

 the column for a thermal disturbance with a minimum bulb- 

 capacity. As regards sensitiveness, it left little to be desired. 

 Some weeks before the start a number of preliminary observa- 

 tions were made with the view of ascertaining the best manner 

 of placing the thermometer and of determining the length of 

 time required for the column to attain a position of rest. By 

 repeated trials it was found that fully five minutes werej needed 

 after placing the thermometer in position before the level of the 

 mercury became approximately constant, both during repose and 

 after a rapid run. Any subsequent variation seldom exceeded 

 Vu of a degree F. The following readings taken from among a 

 number of similar observations will serve to show the extent of 

 the changes from minute to minute after placing the thermo- 

 meter i)i situ: — Time, 7"30 r.M. ; condition, rest. After first 

 minute : Temp., 96°*4 ; second, 97"'9 ; third, 98"*4 ; fourth, 98°'5 ; 

 fifth, 98"-5. Tiiat there is nothing m the rate of change peculiar 

 to the individual is evident from the results of a similar series 

 made at the same time upon another person : first minute, 96°'4J 

 second, 97°*o ; third, 97"5; fourth, 97""8 ; fifth, 97°'8. 



On the day of the attempted ascent we set out from Catania 

 at 5-30 A.M., and drove to Zaffarana. Mouth-temperature 

 before starting, 98''-4. In the carriage, 98°-3 ; time, gh. lom. % 

 pulse, 78. At Zafiarana, 98° "4 ; pulse, 83. As Zaffarana lies at a 

 considerable elevation above the sea-level, the observations so far 

 serve to confirm Dr. Marcet's statement that the rarefaction of 

 the air is without influeAe on the temperature of the body. 

 After a stiff walk of thirty-five minutes, during which the 



