434 



NA TURF. 



[September 23, 1922 



ajther may not be thought of as endowed with the 

 physical properties of material media. It must not 

 be considered as either fixed or moving. No explicit 

 use of any conception of the aether is made in the 

 theory of relativity. It is difficult to see what use 

 could be made of the above views, which are chiefly 

 negative. The phenomena of the gyroscope and 

 Foucault's pendulum (and Sagnac's optical experi- 

 ment), which on the Newtonian ideas are attributed 

 to absolute space, are attributed by relativists to the 

 aether or the effects of the fixed stars — which is 

 rather unconvincing. 



VI. Weyl's Extended Theory (1918). — Whereas 

 Einstein's interval depends only upon gravitational 

 phenomena (although Maxwell's equations and all 

 electromagnetic effects fit into the framework thus 

 constructed), Weyl assumes that the length of the 

 measuring rod depends upon the route it has taken 

 in the neighbourhood of electromagnetic fields. When 

 these are present, the interval is no longer a definite 

 quantity (thus weakening the argument for the 



spectral shift). This theory accounts for Maxwell's 

 equations and introduces Einstein's cosmological 

 term in a natural way, and adds the law of conserva- 

 tion of electricity to those of conservation of momen- 

 tum and energy. On the other hand, it introduces 

 great complexitv into geometry and appears to imply 

 the impossibility of metrology, beyond a certain — 

 very high — degree of accuracy. There is no experi- 

 mental confirmation. Einstein does not accept it. 

 Eddington (1921) has generalised Weyl's mathematics, 

 but says, " Einstein's postulates and deductions are 

 exact. The natural geometry of the world ... is 

 the geometry of Riemann and Einstein, not Weyl's 

 generalised geometry or mine." 



VII. Painleve's Semi-Einsteinian Theory of 

 Gravitation (1922). — This retains Euclidean geo- 

 metry and the old ideas about space and time. By 

 axioms winch are somewhat similar to those of 

 Einstein, but which make no reference to the re- 

 stricted theory, Schwarzschild's form of ds z and the 

 verified astronomical results are obtained. 



Kitchen Ranges. 



THERE is probably no more difficult problem 

 *■ presented to the heating engineer than the 

 kitchen range. So complicated is it that it would 

 appear that no single appliance could possibly be 

 constructed to suit every house or even any large 

 number of houses, and that each installation would 

 have to be adapted to the requirements of the special 

 household. For example, a working-man's cottage 

 usually requires only one fire, which, in the absence 

 of a gas cooker, must satisfy the quadruple duty of 

 heating the room, the oven, the hot-plate and the 

 water, whereas a better class of house might use, and 

 with greater economy, a gas cooker and a coke boiler 

 for the supply of hot water and radiators. Then, 

 again, in an ordinary household, cooking is an opera- 

 tion occupying two or three hours per day only, while 

 hot water is likely to be required at any moment 

 throughout the day. Heating of the rooms is 

 required continuously all day in winter, but not at 

 all in summer. The inevitable consequence of such 

 an intermittent demand is a low efficiency. 



We have before us two important pamphlets 

 embodying the researches of Dr. Margaret Fishenden 

 and Mr. A. H. Barker carried out under the auspices 

 of the Fuel Research Board. 1 Dr. Fishenden has 

 restricted her investigation to the comparative 

 efficiency of ranges fired with ordinary bituminous 

 coal and those heated with the special coke cakes 

 (low temperature coke) produced by the Fuel Research 

 Station at E. Greenwich. She finds that low tempera- 

 ture coke yields a greater proportion of total heat for 

 radiation or for water heating than bituminous coal, 

 while for oven heating the coke compares less favour- 

 ably with coal, the advantage of coke being largely 

 due to radiation effects. She finds, moreover, that 

 in an open kitchen range with back boiler about 17 

 per cent, of the heat of the coal is used for hot water, 

 and in modern designs it varied from 13 to 19 per 

 cent., a result rather higher than that found by Mr. 

 Barker. 



It is unfortunate that Dr. Fishenden's experiments 

 do not include ordinary coke, as the low temperature 

 coke prepared by the Fuel Research Board is a 

 commodity not yet on the market and unlikely to 



Mi) The Efficiency of Low Temperature Coke in Domestic Appliances, 

 by Dr. Margaret W. Fishenden. Fuel Research Board, Technical Paper 

 No. 3. London : H.M. Stationery Office. 1922. 9rf.net. 



(2) Tests on Ranges and Cooking Appliances, by A. H. Barker. Fuel 

 Research Board, Special Report No. 4. London: H.M. Stationery Office, 

 1922. 25. 6d. net. 



appear there, as it is obviously too costly to compete 

 at present with either coal or coke. The report of 

 Mr. Barker (who is lecturer on heating and ventilat- 

 ing engineering at University College, London) deals 

 in a very comprehensive fashion with the whole 

 subject of kitchen ranges, and the results of a large 

 number of practical tests on old and new designs using 

 coal, coke, and gas as sources of fuel. The introduc- 

 tion to the report contains the following statement : 

 " In the design of British cooking ranges, attention 

 has hitherto been mainly devoted to securing cheap- 

 ness of construction and convenience of use. Economy 

 in fuel consumption has only played a minor part in 

 determining the different types in use. The shortage 

 and high price of coal have, however, emphasized the 

 necessity for fuel economy and, consequently, of an 

 examination of the efficiency of British kitchen ranges. 

 . . . The strong prejudice in favour of an open-fronted 

 fire appears to be peculiar to this country. In most 

 other countries a cooking range fire is usually closed. 

 ... In view, therefore, of the scarcity and high price 

 of coal at the present time, it appears to be a matter 

 for serious consideration whether steps should not 

 be taken to encourage the more general adoption 

 in this country of ranges which are more economical 

 in fuel consumption than those of ordinary British 

 design." 



In his general summary Mr. Barker has arrived at 

 the following conclusions : that the general efficiency 

 of all ranges on the market at the present time is low, 

 the actual oven efficiency ranging from 0.75 to 5 per 

 cent., the usual being about 2 per cent., that of the hot 

 water supply from 7 to 17 per cent, or usually 11 per 

 cent., and the hot plate from 1 to 12 per cent, or 

 generally below 6 per cent. He estimates that the 

 modern type of range wastes 85 per cent, of the fuel 

 in heating the air of the kitchen (about 30 per cent.), 

 by absorption in the brickwork (about 30 per cent.), 

 and lost in the flue gases (about 25 per cent.). 

 Economy may be effected by not setting ranges in 

 brickwork, by preventing leakage of cold air into the 

 furnace and flues, and by doing away with the hot- 

 plate or covering it when not in use, and also the 

 oven door, with non-conducting material. He ad- 

 mits, however, that these losses are unavoidable if 

 the present convenience and cheapness of the ordinary 

 range are to be retained and one fire made to serve 

 so many different purposes. But if the efficiency 

 is considered irrespective of convenience, cheapness, 



NO. 2760, VOL. I IO] 



