472 



KNOWLEDGE. 



Df.cember, 1911. 



THE COAL RESOURCES OF 

 KINGDOM. 



THE UXITl-D 



To the Kditars of " Kmiwledgic." 



Sirs. — Attention has again bt-fn attracted to the contents 

 of onr natnral coal store. Experts have pointed ont that we 

 are rapidly exhausting the coal resom'ces of our coiuitry, and 

 they estimate the life of our coalfields to be less than two 

 hundred years. Half a century ago, experts gave a similar 

 estimate, and we have during the last fifty years withdrawn 

 millions of tons from the natural store. 



It is of interest, and as well assuring, to note that whilst the 

 Royal Commission of 1871 estimated the "available coal" at 

 yO,207, 285,000 tons, the final report of the 1905 Commission 

 gave the quantity of available coal as 100.914,568,167 tons. 

 Thus the figures of the last Commission exceeded those of 

 1871 by 10,707.383,167 tons, and it must be considered that 

 during the period 1871-1905. no less than 5.694.928,507 tons 

 had been brought to bank. 



Since the last Commission sat, there ha\e been considerable 

 additional coal areas proved in Lincolnshire and in the South 

 of England. A reasonable survey of the coal "in store" 

 within the United Kingdom gives ample assurance that onr 

 coal supplies are safe for the next five hundred year.s. 



National economy requires a periodical stocUtaUing of 

 available coal, and demands that the coal drawn from the 

 natural store shall be economically utilized. 



Every ton of coal mined reduces the assets of the nation, 

 and it is a national duty to prevent avoidable waste, in 

 (rt) winning coal from its natural bed. and (6) in the con- 

 version of the potential energy of the coal into useful work. 



Few people realize the amount of power which is stored 

 in coal. One tea.spoonful of British coal contains sufficient 

 energy to lift two modern locomotives to a height of one foot. 

 .A piece of coal the size of a man's fist has power enough to 

 throw a weight of thirty pounds to a height of one-and-a- 

 quarter miles. In our houses we use coal by the shovelful : 

 but if the heat stored in the coal was efficiently utilized the 

 coal-spoon would displace the shovel. To boil a gallon of 

 water we require a large fire ; yet the heat produced by one 

 pound of coal is sufticient to raise to boiling point one hundred 

 pounds or ten gallons of water. 



Industrially we only utilize one-tenth of the power stored in 

 coal : the balance (nine-tenthsl is used up or wasted in the 

 process of securing the one-tenth. 



A National C'onservancy is needed to protect the national 

 store of solid fuel, and to obtain a better efficiency in the 

 every-day use of coal. The industrial and maritime power and 

 progress of our nation is founded on the enormous stores of 

 first-grade coal and the large annual production. 



Within the United Kingdom no less than two hundred 

 millions of tons of coal are consumed annually, and the yearly 

 export is well over sixty millions of tons. The important 

 bearing of these figures on our national industries is quite 

 obvious. 



It is a national duty to win every ton of coal from the 



natural store in the most economical manner possible, and to 



obtain from the coal produced the highest possible value. 



. These points are worth the attention of the nation's economists, 



and provide a wide field for profitable scientific investigation. 



.MVLi:S BROWN. 



QUERIES AND ANSWERS. 



Readers are invited to send in Onesfions and to answer the Queries whicli are printed here. 



gUESTIONS. 



55. THE NEW ASTRONOMY.— I should be very grateful 

 for any information as to the v.iriability of double stars, and 

 especially I should like to know of binaries that are doubly 

 variable. If spectroscopists would look for lines of planetary 

 nebulae about variable doubles, about the Cepheids, and about 

 variables whose light curve ascends more quickly than it 

 descends, they might supply useful information. I should 

 also be glad to know if another variable could be found in the 

 neighbourhood of variables with that kind of light curve when 

 one exists alone. It would also be valuable to the theory to 

 find if nebulosity at minimum exists in the case of any of the 

 Cepheids. On page 80 in "The Birth of Worlds and Systems '' 

 (Harper's Library of Living Thought). 1 have given a table of 

 variables that I picked out from Gore's list; nebulosity should 

 be looked for between the constituents of each pair, or perhaps 

 surrounding them if close. The lines of planetary nebulae 

 should also be looked for about them. The old measures 

 should be compared with the new ones, to see if the stars are 

 still separating, or if they are in long ellipses. Their exact angle 

 and distance should now be determined to make future com- 

 parisons. I should also be pleased if the position where novae 

 have appeared were examined for nebulosity, for faint fluctua- 

 tions of light, and for the lines of planetary nebulae. The 

 Owl and Dumb-bell nebulae seem to me to be planetary nebulae. 

 I should be glad to know if they show the characteristic lines: 

 the singular bilateral symmetry suggests that each is a third 

 body struck from grazing suns. In the case of the Owl the 

 eyes may be the two original moderately rare bodies; it 

 would be interesting to know if any changes of form or 

 structure in these or other planetary nebulae have been 

 observed, and it would also be desirable to know the several 

 chemical elements of the sphere-in-sphere constituents of these 

 nebulae. 



Mr. McCarthy, in his encouraging letter, speaks of the exact 

 comparison he fintls to exist between the deduced properties 

 of the tliird body and those observed in Nova Hersei. 



Mr. Rafi'ety is a careful spectroscopic student: I should like 

 to know if he has compared the two. and to have his opinion 

 as to temporary and variable stars being the result of partial 

 impact and the third body. ^ ^^. gjcKERTON. 



56. WATER SNAILS [PLANORBIS CORNEUS).— 



Would one of your readers describe the parasite of the Water 

 Snails iPlanorbis Cornells, and so on). It appears to eat 

 into the shell and ultimately causes the death of the host. 



J. M. 



57. SOLAR SPECTRUM.— Why in photographs of the 

 solar spectrum from diffused daylight (a bright sky) the lines 

 are never sharp, as in the case from direct sunlight, though 

 the slit has the same width ? r A S 



58. In a train of prisms for great dispersion, is there 

 interference of light where the two beams of light cross ? 

 If not, why ? .And if there is, why is there no interference 

 effect in the spectrum ? 



C. A. S. 



ANSWERS. 



51. THE GEOLOGY OF SOUTH DORSET.— 

 Information asked can easily be obtained by turning up 

 " Kelly's Directory of Hampshire. Wiltshire, Dorsetshire and 

 the Cliannel Isles, 1907," where an outline of the Geology of 

 Dorsetshire is ably described by W. Jerome Harrison, F.Cr.S., in 

 which he not only gives a full account of the Strata. .Minerals, 

 and Fossils, but also of the names and writers of the mmierous 

 books treating on the Geology of the district. There is also 

 a splendid collection of fossils in the Museum at Dorchester. 

 The publications of the Government geological survey maps 

 and reports. Map Sheet 16, Poole. Wareham and Swanage, 

 take up the latest details : these can be obtained from 

 .Mr. Henry Ling. Bookseller. Dorchester, Dorsetshire. 



A. .M. W. 



