532 



NA TURE 



[September 29, 1898 



empire is still expanding, and we and our competitors in that 

 field are still absorbing new districts — a practice which will 

 probably continue as long as any spot of ground remains on the 

 face of the globe occupied by an uncivilised race. 



Would it not be worth while at this juncture to extend to the 

 peoples of Africa, for instance, the principles and methods of the 

 Ethnographic Survey — to . study thoroughly all their physical 

 characters, and at the same time to get an insight into the 

 working of their minds, the sentiments and ideas that affect them 

 most closely, their convictions of right and wrong, their systems 

 of law, the traditions of the past that they cherish, and the 

 rude accomplishments they possess? If for such a service 

 investigators like Dr. Roth, who began his researches in 

 Queensland by so close a study of the languages and dialects of 

 the people that he thoroughly won their confidence, could be 

 found, the • public would soon learn- the practical value of 

 anthropological research. If the considerations which I have 

 endeavoured to urge upon you should lead not only the scientific 

 student but the community at large to look upon that which is 

 strange in the habits and ways of thinking of uncivilised peoples 

 as representing with more or less accuracy a stage in that long 

 continuity of mental progress without which civilised peoples 

 would not be what and where they are, it could not but favour- 

 ably affect the principles and practice of colonisation. Tout 

 comprendre c'est tout pardonner. The more intimate our 

 acquaintance with the races we have to deal with and to sub- 

 jugate, the more we shall find what it means to stand with them 

 on the same platform of common humanity. If the object of 

 government be, as it ought to be, the good of the governed, it 

 is for the governing race to fit itself for the task by laying to 

 heart the lessons and adopting the processes of practical 

 Anthropology. 



PHYSICS AT THE BRITISH ASSOCIATION. 

 'TTHE reputation for industry which Section A has acquired in 

 past years will not suffer in any way by the proceedings 

 of the recent meeting in Bristol. In addition to the ordinary 

 meetings of the Section, the International Magnetic Conference 

 met on four days ; and as all communications to the Section 

 relating to terrestrial magnetism and atmospheric electricity 

 were referred to the Conference, it may be said that the Section 

 sat in duplicate on five out of its six days of meeting. On 

 Saturday, when the Magnetic Conference did not meet, the two 

 departments were devoted to mathematics and meteorology 

 respectively, and on Wednesday 'the Section was not divided. 

 On two occasions the Section was associated with others in 

 joint discussions, namely with Section B, on the results of the 

 recent solar eclipse expeditions, and with Section G, on the 

 magnetic and electrolytic effects of electric railways. The 

 members of the International Magnetic Conference also took 

 part in the latter discussion. The papers read before the Section 

 were representative of almost every branch of physics. In the 

 following account they are grouped according to subject, and 

 are not arranged in the order in which they were read. 



Before the commencement of his address the President, 

 Prof. Ayrton, referred to the loss to science occasioned by the 

 death of Dr. John Hopkinson. The address, which was pub- 

 lished in Nature of September 8, suggests a new field for 

 physical and chemical research, namely the investigation of the 

 phenomena of smell. For the physicist the most striking 

 experiments described are those which show the slowness of 

 diffusion of odorous particles in still air, and the absorption of 

 scents by glass, while the physiologist cannot fail to be interested 

 in the superior sense of smell possessed by the female sex. In 

 moving a vote of thanks to the" President, Lord Kelvin referred 

 to the identity of the senses of taste and smell, including both 

 as the chemical sense, and hoped Prof. Ayrton's address would 

 lead to another bond of union between the chemist and the 

 physicist. Prof. Mascart seconded the vote, specially thanking 

 the President for his welcome to the members of the Inter- 

 national Magnetic Conference. 



In the subject of heat Prof. Rosa described the continuation 

 of important work by himself and Prof. Atwater, the object 

 being to determine whether the law of conservation of energy 

 holds good for the vital processes going on in the human body. 

 F^r this purpose a space large enough for a man to live in was 

 enclosed as a calorimeter, and surrounded by alternate jackets of 

 flowing water and air, in such a manner that the heat evolved 



NO. 1509, VOL. 58] 



from the " calorimeter " could be accurately measured. The 

 details of construction of the apparatus were described at the 

 Toronto meeting last year. During the past twelve months the 

 authors have made experiments on men living in the calori- 

 meter for periods varying from four to eight days, and doing 

 different kinds of work. The heat-value of the food supplied and 

 of the excreta were obtained by combustion, and the amount and 

 composition of the gases entering and leaving the calorimeter 

 were also determined. A full description of the work is to be 

 published by the United States Government, under whose 

 auspices the experiments have been carried out ; it may, how- 

 ever, be stated that the law of conservation of energy is found 

 to be true within the limits of experimental error. The ratio of 

 the mechanical work done by a man to the total energy supplied 

 to him, that is to say his efficiency as an engine, is usually about 

 7 per cent., and may be as high as 10 per cent. These figures 

 are higher than the efficiency of a perfect heat-engine working 

 between the same limits of temperature, and lead us to the con- 

 clusion that the energy transformation in the human body is not 

 effected solely by heat, but is most probably analogous to that 

 in a circuit containing a battery and electromotor. 



Another series of experiments to decide a question of theo- 

 retical interest was described in a paper by Dr. A. Gait, on the 

 heat of combination of metals in the formation of alloys. Lord 

 Kelvin has shown how a lower limit to the size of atoms may 

 be found by comparing the work done by the approach of the 

 electrical charges on a thin film of zinc and a thin film of copper, 

 their difference of potential being that due to contact, with the 

 heat of combination of the films to form brass. On the other 

 hand Prof. Oliver Lodge has pointed out ^ that on the chemical 

 theory of electromotive force of contact the heat of formation of 

 an alloy should be much smaller than Lord Kelvin assumes it ta 

 be, and an exact determination of its value would form a crucial 

 test between the rival contact and chemical theories. In Dr. 

 Gait's experiments a thin glass bulb with holes in its sides con- 

 tains the alloy or the mixed metals, and is lowered into a calori- 

 meter of glass containing nitric acid ; as the acid passes through 

 the holes the metal is dissolved, and the evolved gases do not 

 escape. The rise of temperature of the acid is noted, and the 

 heat of combination calculated. The results are so far pre- 

 liminary, and the Association has made a grant for their con- 

 tinuation. Mr. W. N. Shaw read a paper on Dalton's law, in 

 which he called attention to Regnault's experiments on the 

 pressure of mixtures of air and saturated ether vapour ; these 

 experiments show a discrepancy between the saturation pressure 

 of ether in air and in a vacuum. The explanation afforded by 

 Regnault is that errors are introduced owing to the condensation 

 of vapour on the vertical walls of the barometer tube ; but from 

 experiments on mixtures of air and water-vapour, Mr. Shaw 

 considers that a real departure from the law of Dalton is 

 indicated. The subject is to be investigated in the Cavendish 

 Laboratory. Dr. C. H. Lees described experiments on the 

 thermal conductivity of rocks at different pressures, according to 

 which the conductivities of slate, granite and marble are very 

 slightly increased by increased pressure, while in the case of a 

 rather soft sandstone the increase amounted to 3 per cent, under 

 a pressure of about sixty atmospheres. Mr. S. R. Milner and 

 Prof. Chattock read a paper on the thermal conductivity of 

 water, which they find to be 0-00143 C.G.S. units at 20° C. 



Among papers relating to light Mr. J. W. Gifford read a 

 communication on lenses, not of glass, in which he compared 

 the transparency of calcite, quartz and fluor-spar for extreme 

 ultra-violet rays, the last-named being the most transparent. 

 Lord Kelvin discussed the various theories of refraction and 

 anomalous dispersion, and stated that none of the dynamical 

 theories hitherto proposed is satisfactory or free from difficulties. 

 Prof. T. Preston described his experiments on radiation in a 

 magnetic field. Zeeman found that when the spectrum of the 

 sodium light emitted from a source in a magnetic field is viewed 

 at right angles to the lines of force, the bright lines are tripled 

 and the polarisation of the side lines is in a plane perpendicular 

 to that of the central line. By using a very large grating and 

 photographing the lines. Prof. Preston finds that all bright lines 

 in a spectrum are not treated alike ; some are unchanged, some 

 become doublets, triplets, quartets, or even sextets. He ex- 

 plained how absorption of the original radiation by vapour 

 surrounding the source might account for the multiplication of 

 lines, but he considers from the sharpness of definition of the 

 lines that the effect is not due to absorption. Prof. S. P. 

 ^ Philosophical Magazine., vol. xix., 1885. 



