28 



NATURE 



\_May 12, 1 88] 



elusion that a sen5e of the beautiful and an admiration 

 for the forms and colours of nature is only a strongly 

 developed instinct inherited from the lower animals ! An 

 uneasy feeling is raised not only that the rebuke adminis- 

 tered to " man, the most conceited creature," by the flea in 

 Gay's fable is well deserved, but that the description there 

 given of the views taken by other members of creation 

 are far more probable and even reasonable than ever their 

 author thought. 



It would very much help the less scientific public to 

 accept the doctrine of development if by it any imaginable 

 explanation of the part an insect takes in its own meta- 

 morphosis, or its feelings of personal identity through the 

 states of grub, chrysalis, and iDutterfly, could be suggested ; 

 but an attempt explaining so little as chapter xv. must 

 only make the incredulous close the book more sceptical 

 still. W. O. 



An Elementary Course of Practical Physics. By A. M. 

 Worthington, M.A., F.R.A.S,, Assistant Master at 

 CHfton College. 51pp. (London: Rivingtons, 1881.) 

 This extremely useful and carefully prepared little book 

 is intended to form the basis of the practical teaching of 

 physics for schoolboys. It describes the way of per- 

 forming fifty-eight experiments in elementary physical 

 measurements. It appears therefore to have exactly 

 struck the right line between the Scylla and the Charybdi's 

 of practical physics, in which a middle course between 

 " merely qualitative work only leading to play " and 

 " measurements by costly instruments requiring on an 

 average two hours for each experiment," appears to be 

 difficult to steer. Mr. Worthington, whose experience in 

 teaching of this kind is considerable, has embodied the 

 results of his labours in the present compendious little 

 volume, and were the course he has sketched out adopted 

 in all our public schools the gain to physical science 

 would be great. There can be no doubt that one great 

 drawback to the progress of students in physical labora- 

 tories even at the Universities is the want of acquaintance 

 with the common instruments and with the principles of 

 exact measurement. Mr. Worthington's course cannot 

 fail to give this, and to teach moreover something of 

 manipulation, e.xact observation, and of use of algebra 

 and geometry as applied to real quantities. The acquiring 

 of intelligent and orderly methods of recording observa- 

 tions is facilitated wherever possible by providing a blank 

 schedule or form wherein to enter the various observations 

 and their several corrections, and for comparison between 

 the observed and computed results. The course com- 

 prises experiments in elementary mechanical measure- 

 ments, centre of gr.ivity, specific gravity, elasticity of 

 cords, law of pendulum, &c., and also includes experi- 

 ments upon the law of Boyle and upon the laws of 

 expansion by heat and of specific heat. We trust it will 

 not be long before Mr. Worthington adds a course of 

 practical experiments in other branches of physics to the 

 present series. He deserves the thanks of all who have 

 to teach physics in the laboratory to beginners in mani- 

 pulation. 



LETTERS TO THE EDITOR 

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 by his correspondents. Neither can he undertake to return, 

 or to correspond with the writers op, rejected manuscripts. 

 No notice is taken of anonymous communications. 

 [ The Editor urgently requests correspondents to keep their letters 

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Hot Ice 



As my name lias beeu mentioned in Nature in connection 

 with Dr. Carnelley's experiments on hot ice it may possibly be 

 convenient if I describe the experiments in which I have failed 



to rai^e the temperature of ice and camphor above their fasing- 

 points when they are heated in vacuo. 



On Decemljer 16, I was present at the meeting of the Chemical 

 Society, when Dr. Carnelley showed his experiments with ice, 

 camphor, and mercuric chloride. At the time they did not 

 appear conclusive to me, for it seemed (although in this I am 

 p jssibly mistaken) that tlie thermometer bulb; were too close to 

 the sides of the containing tubes and that they consequently did 

 not indicate the temperatures of the solids. 



A few days afterwards I tried an experiment with camphor in . 

 an apparatus so arranged that the thermometer was held rigidly 

 in the axis of a glass tube with the bulb in the middle of a block 

 of camphor which had been previously melted in the tube. The 

 apparatus was exhausted by a water air-pump, and the tube con- 

 taining the camphor heated. No fusion took place, and the 

 camphor volatili-;ed rapidly ; but the thermometer did not indi- 

 cate a temperature as high as 157° C. The exact temperature 

 could not be ascertained, for a part of the thermometer stem was 

 hidden by the caoutchouc which connected it to the tube. The 



fusing point of the camphor being 176°, it is certain that the 

 temperature was far below thi-;, although the glass tube was 

 softened and there were indications of decomposition of the 

 camphor vapour by contact with the hot glass. 



Air was afterwards admitted, the camphor fused down, and 

 the air exhausted until the liquid just solidified. Heat was then 

 r.apidly applied, but the temperature remained between I70°'2 

 and 172° until a portion of the thermometer bulb was exposed, 

 when the temperature began to rise. Dr. Carnelley has since 

 informed me that he has obtained precisely similar results with 

 camphor. 



On December 30 an experiment was tried with ice in an 

 apparatus bearing a remarkable resemblance to one recently 

 described by Prof. Lothar Meyer (Ber. Deut. Chem. Ges. xiv. 

 718, April II). The tube A is surmounted by a narrower tube, 

 in which the thermomeicr stem was fixed by a piece of caout- 

 chouc tube, the joint being surrounded by a tube containing 

 mercury. To the side of A a tube about half an inch in diameter, 

 connected with a copper flask of half a litre capacity, is joined, 

 a branch from this wide tube leading to a Sprengel pump. The 



