172 



NATURE 



{June 21, 1888 



Plotting, or Graphic Mathematics. By R. Wormell, 

 D.Sc, M.A. (London : Waterlow and Sons, Limited, 

 1888.) 



This book is intended chiefly for those who have 

 mastered the beginnings of algebra and Euclid, and so is 

 very elementary. The method employed throughout is 

 that of using squares, and preparatory exercises are first 

 given to show the student the different purposes to which 

 they may be applied with facility. Proportion and the 

 determination of areas are the subjects of the first two 

 chapters, followed by a chapter on the tracing of paths 

 of projectiles, with various data. The sections of the 

 cone, such as the parabola, ellipse, and hyperbola, are 

 next described, with various methods of tracing them. 

 The book contains a great number of numerical examples, 

 and concludes with a chapter on the higher graphs and 

 curves of observation. 



The Elements of Logarithms. By W. Gallatly, M.A. 

 (London: F. Hodgson, 1888.) 



In this little book of thirty-one pages the various rules 

 and methods of treating logarithms are stated and 

 explained in a simple and precise way, and those 

 beginning the subject would do well to read through 

 these few pages. Numerous examples are put in here and 

 there, and at the end the author has added a collection of 

 questions taken from the Woolwich and Sandhurst 

 examination papers for the years 1880-87. 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he under- 

 take to return, or to correspond with the writers of, 

 rejected manuscripts intended for this or any other part 

 of Nature. Mo notice is taken of anonymous communi- 

 cations.] 



Thunderstorms and Lightning Accidents. 



As the season of thunderstorms and lightning accidents is 

 now approaching, I hope you will kindly allow me to make 

 known through your columns the fact that, in the interests of 

 science, the Institute of Medical Electricity is very desirous of 

 obtaining authentic information concerning lightning accidents, 

 whether fatal or otherwise. I should therefore esteem it a 

 favour if some of the many friends of humanity among your 

 readers will assist us to investigate these phenomena by sending 

 me such particulars of accidents of this nature as they may have 

 personal or trustworthy knowledge of as soon after they occur as 

 possible. 



Of course, electrical and physiological details are what we 

 most require, but trustworthy general information is often valuable, 

 and will be gratefully received. 



24 Regent Street, S. W. H. Newman Lawrence. 



Nose-Blackening as Preventive of Snow-Blindness. 



I ONLY read Prof. Ray Lankester's letter the other day on the 

 above, which appeared in Nature of May 3 (p. 7). I have 

 made inquiries among travellers in the snow regions of North 

 America, and find the practice to be quite common and well 

 known, but have met with no one who can explain it. I may 

 say, however, that when I visited New Zealand in 1884 there 

 were in one of the canoes which came off to our ship several 

 naked natives, who had disfigured their faces by blackening their 

 noses and eyes, and running a black fillet round the face, which 

 gave them a villainous aspect ; and I, in that insolent ignorance 

 which seems to prevail with all pious people who have dealings 

 with "the heathen of the isles," believed they had got them- 

 selves up in this way in order to frighten us. But it may well 

 have been for other reasons. Certainly the sun's heat, reflected 

 from the still waters of the sea, was quite as painful as any I ever 

 felt in the regions of the silver snow. I subsequently found that 

 the black used by these people, who are of a pale complexion, 

 was the oxide of manganese, called in their tongue labdn. 



A. J. Duffield. 

 The Delaware, Keweenaw Michigan, U.S.A., June 4. 



The Lethrus ccphalotes. 



The beetle which is described in your issue of June 7 (p. 

 134), by the British Consul at Varna, is probably the Lethrus 

 cephalotes, which has proved so destructive to vineyards in East 

 and South-East Europe. It is a dull black beetle, easily 

 recognized by the swollen truncated ends of the antennre ; its 

 length is about 21 mm. It lives chiefly in dry and sandy soil, 

 and during dry weather the beetles leave their holes generally 

 between nine and eleven in the morning and after three in the 

 afternoon, to attack the tender parts of the vine, as Mr. Brophy 

 describes. 



Taschenberg is of the opinion that the buds, &c, of the vine 

 which are dragged back to the holes of the beetles serve as food 

 for the larvae. As the beetles show a marked aversion to water, 

 it is possible that the pest might be lessened by copiously watering 

 the infected areas. Arthur E. Shipley. 



*\ Christ's College, Cambridge, June 16, 



Proposed Fuel-testing Station fori'London. 



Will you allow me to put before your readers the following 

 proposition for the establishment of such a station, the desirability 

 of which has been much impressed upon me within the last few 

 years ? So far as I know, there does not exist anything of the 

 kind in this country where, as on the Continent, coals can be 

 tested for their evaporative power, the gases of combustion 

 analyzed, and all the results carefully reported on by experts. I 

 subjoin a few details of the proposed station, with probable cost. 

 It should, I consider, be placed on a perfectly independent foot- 

 ing, and managed by experts, under a small committee appointed 

 by those who assist with money or otherwise. It might follow 

 generally the lines of existing coal- testing stations, but with all 

 modern improvements. 



In this country it is remarkable that neither the sellers of coal 

 take the trouble to find out how much heat they are offering, nor 

 the purchasers how much they are getting for their money, and 

 this notwithstanding the hundreds of millions of tons of coal chang- 

 ing hands yearly. Colliery-owners and coal-merchants, as well as 

 the large consumers, know very little about coal calorimeters, 

 although the former sell so much heat, and the latter try to utilize 

 it to the best advantage. How few of the latter weigh their coal 

 regularly, or keep any weekly record of the quantities of ashes 

 and clinkers, to find out how much dirt and incombustible matter 

 they are paying for ! How few know what it costs them in fuel 

 to evaporate one thousand gallons of water into steam, which is 

 one of the best standards of comparison in a given district ! 



Locality. — The station might be in close proximity to a river, 

 canal, or railway-station, so that the coals could be delivered easily 

 and cheaply, and the steam allowed to escape under pressure 

 without causing annoyance. A small piece of land doubtless 

 could be obtained in such a situation at a low rent. The boiler- 

 shed should be about 35 x 20 feet, with a small additional shed 

 for storing the fuel. 



Cost. — It would be desirable to allow at least ^700 for a 

 start, to cover the cost of the boiler-shed, chimney, 20 horse- 

 power boiler (if such were considered large enough), and the 

 special arrangements for measuring the feed-water with tanks, 

 scales, feed-pump, injector, gas and coal analyzing apparatus, 

 calorimeters, &c. Seeing that until the objects of the station 

 become known it would probably not pay expenses, the help of 

 guarantors would no doubt be necessary. 



Yearly Expenses. — The charge for testing and reporting upon 

 each combustible would probably more than cover eventually the 

 salaries of a technical manager, his assistant, and the stoker. 

 Some arrangement might possibly be made by which the manager 

 and his assistant should only attend when required, at any rate at 

 first, in order to diminish expenses. 



The station would require to be advertised and made known in 

 various ways. Colliery-owners would no doubt find it to their 

 advantage to have their different kinds of coal tested and reported 

 upon, so as to offer them to their customers with their ascertained 

 heating value or evaporative power. Large consumers of coal 

 (railway companies, water-works, and others) should know the 

 heating value of the coal they are paying for, and the percentage 

 of incombustibles. 



I add a few notes on the temporary and permanent experi- 

 mental heat stations known to me. 



(1) The earliest fuel-testing station was established in 1847 at 

 Brix, in Germany. 



(2) Sir H. de la Beche and Dr. Lyon Playfair made a series of 



