208 



NA TURE 



[January 2, \^C2 



Ihe exposure. Among the apparatus used is a pendulum photo- 

 chronograph, in which the pendulum carries a sensitive plate and 

 is provided with a contrivance for releasing it at will and fixing 

 it at the end of each half-oscillation. The pap3rs are illustrated 

 by photographs of the curves of different vowel sounds, taken 

 in the laboratory. 



The problem of the perfectly irresistible body impinging on 

 a perfectly impenetrable obstacle is scarcely mire paradoxical 

 thin Poinsot's problem of a rigid body having two points fixed, 

 when it is proposed to calculate the actual reactions and not 

 merely the sum of the reactions along the line joining the points. 

 The Bulletin of the Belgian .\c.idemy contains reports on a 

 paper by M. Fijrron, in which that author endeavours to over- 

 come the indeterminatenesi of the problem by replacing the 

 force Z at any point in the body by its components in the lines 

 joining its point of application to the two fixed points. One of 

 the referees of the paper, M. Ch. Lagrange, objects to the 

 principle of tr.ansmission of force being applied in this case, 

 but he does not hesitate to apply it in a piper of his own, in 

 which he seeks to prove that each of the reactions is equal to 

 iZ. 



A THEORY of progressive taxation, capable of being repre- 

 sented by simple mathematical formula;, is discussed by Mr. G. 

 Cassel in the Econonik Journal iox December. It is pointed out 

 that the same results that are obtained by means of a graduated 

 income-tax can equally well or better be effected by levying a tax 

 at a constant rate per cent, and allowing suitable deductions to 

 be exempted from taxation. Moreover, if a tax is to produce 

 "equal sacrifices" the amount which should h% exempted from 

 taxation should be larger for large than for small incomes, as 

 the cost of living consistent with efficiency increases with the 

 amount of income to be earned. Mr. Cissel's proposal is based 

 on the supposition of a " minimum of subsistence" representing 

 the income exempt from taxation, and a "maximum of 

 subsistence" representing the cost of living consistent with 

 efficiency in earning an infinite income. The amount deducted 

 for subsistence and the rate of taxation are then represented by 

 formulx of the form known to mathematicians as "homographic 

 transformations. " 



In the use of the wet and dry bulb thermometer for 

 determining the pressure of aqueous vapour in air, consider- 

 able uncertainty is introduced by the presence of a constant 

 which varies according to the conditions under which the 

 thermometers are placed. The extremes are represented liy 

 August's formula, which supposes the air round the bulbs to be 

 constantly changing, and Maxwell and Stefan's result, which 

 is calculated on the hypothesis that the water on the bulb is 

 evaporating and its vapour difi'using into an infinite mass of 

 quiescent air. Signor G. Guglielmo, writing in the Aiti da 

 Lineei, x. 9, now proposes to eliminate the arbitrary constant 

 by the use of a //»></ thermometer, the bulb of which is wetted by 

 an aqueous solution the vapour tension of which differs consider- 

 ably from that of pure water. In this way a further equation is 

 obtained and the unknown constant is eliminated. Some 

 preliminary experiments are quoted showing the efficacy of the 

 method. The difficulties of applying it arise from the change 

 in concentration of the solution caused by evaporation, and the 

 consequent uncertainty as to its latent heat. But could not a 

 second volatile liquid be substituted for the saline solution ? 



At a recent meeting of the Meteorological Society of 

 Mauritius, the secretary, Mr. T. F. Claxton, read an interest- 

 ing paper on the objects for which that Society was established, 

 in the year 1851. These were, chiefly : — To provide for regular 

 observations in Mauritius and its Dependencies (Rodrigues, 

 Seychelles, Diego Garcia, &c.), the establishment of a per- 

 NO. 1679, VOL. 65] 



manent observatory, and the collection and tabulation of 

 observations taken in the Indian Ocean. Some of these 

 objects have been successfully carried out, as shown by the 

 Transactions of the .Society and the annual reports of the 

 Royal Alfred Observatory. The establishment of this observa- 

 tory (in 1874) was perhaps the most important achievement of 

 the Society ; it is .supported entirely from Government funds, and 

 the director has always been the secretary of the Society. Every 

 ship visiting the island is boarded and permission requested to 

 extract observations for the construction of charts. Cyclone 

 tracks of the Indian Ocean were published in 1S91 and are of 

 great use to navigators at the present time, and an important 

 work has recently been commenced, viz. the tabulation into 

 5° squares of all the information collected from the log-books of 

 vessels that have traversed the Indian Ocean since 1S54, with 

 the view of constructing a meteorological atlas of the south 

 Indian Ocean ; this will doubtless be of much pr.ictical use to 

 sailors. Unfortunately, there has been a steady decrease in the 

 number of vessels trading with Mauritius, from 7S7 in the year 

 1878 to 283 in 1900, so that the construction of daily synoptic 

 weather charts begun by Dr. Meldrum about i860 has had to be 

 discontinued, except during cyclone weather. 



The Imperial Department of Agriculture for tht West Indies 

 has issued a second, and revised, edition of Mr. Maxwell- 

 Lefroy's pamphlet on " The General Treatment of Insect Pests." 

 Another of the pamphlet series, No. 11, "Hints for School 

 Gardens," by the technical assistant, Mr. William G. Freeman, 

 has just been published. It deals, in simple language, with the 

 most elementary principles of agriculture, taking Imx and pot 

 cultivation as the starting point for school work, and going on 

 to gardening — growing vegetables and flowers and experimenting 

 with manures. Mr. Freeman has written a useful handbook, 

 which should be studied by teachers with Mr. Watts's " Nature 

 Teaching " recently noticed here. 



In his annual report on the Antigua Botanic Station, Mr. 

 W. N. Sands, the curator, gives a complete summary of the work 

 for the year ending March 31, 1901. The most interesting feature 

 of the report is a detailed account of an experiment designed to 

 ascertain what a small plot of land about the size of a peasant 

 garden or negro ground would produce in provisions, if properly 

 managed and arranged. The usual method adopted by the 

 peasantry is to grow one or two crops only, and for which they 

 have to wait about five months for a return, which is often poor, 

 and then selling out for a few shillings, often pence. At the 

 Botanic Station a patch l/ioacre in extent, and overgrown with 

 grass, was taken in hand, and, having been duly cleared, forked 

 and manured, nineteen varieties of vegetables were sown or 

 planted at various periods. In due time such of them as matured 

 were reaped, and sold locally. The sum real ised for the produce 

 of the patch was 2/. 15^., the expenditure having been I/. 15J. 3(1'. 

 Of the latter sum, however, i/. 45. Si/, was expended on labour, 

 which would not come out of the peasant's pocket, as he would 

 attend to his garden in his spare time. By the exercise of a 

 little intelligence, therefore, a peasant could make a profit o. 

 2/. 4r. $(/. out of i/io acre of land in nine months. 



The most important paper in the Transactions of the Hull 

 Scientific and Field Naturalists' Club for 1901 is one by Messrs. 

 F. W. Mills and R. H. Philip on the diatoms of the Hull 

 neighbourhood. It is illustrated by no less than sixteen plates, 

 drawn by the first-named author. 



The October issue of the Bulletin of the Cracow Academy 

 of Sciences contains an important article, by M. Godlewski, on 

 the development of muscular tissue in mammals ; and a second, 

 by M. Przesmycki, on certain protozoans parasitic in rotifers. 

 Both are elaborately illustrated. 



