4o6 



NATURE 



[May 27. 1920 



are several slips and misprints; on plate ii., Figs. 4 

 and 5 are transposed, according to the description; 

 on p. 28 the word "visible" appears to be a mis- 

 print for "recessive"; and on p. 86, 1. 26, "female" 

 is printed for "male," etc. But apart from these 

 slips and the rather inconvenient arrangement of the 

 subject-matter, the work is the most valuable on the 

 subject of gynandromorphism with which we are 

 acquainted. 



Space does not allow of more than a brief reference 

 to the other three parts. Part ii. discusses in detail 

 all the mutant characters that have occurred in "the 

 second chromosome," i.e. those characters belonging 

 to the second linked group which are not sex-limited 

 (sex-linked) in inheritance. Full data of crossing- 

 over ratios are given, and on the basis of these a 

 map of the chromosome is constructed, like those 

 previously published for the X-chromosome. Part iii. 

 deals with inherited linkage variations in the same 

 group, and it is concluded that two factors, the posi- 

 tion of which in the series is determinable by their 

 linkage relations, reduce the amount of crossing-over 

 between certain factors without altering their sequence 

 in the series. Part iv. describes the isolation by 

 selection of a factor which affects the extent of 

 development of the character " notch " in the wing, 

 and proves that change resulting from selection is 

 due, not to an alteration in the factor for "notch," 

 but to the presence of a distinct modifying factor. 

 It is also shown that Castle's hypothesis of con- 

 tamination by heterozygosis is untenable. 



Finally, it is impossible to read the facts presented 

 in this volume without being impressed by the great 

 strength of the evidence for Morgan's theory that 

 Mendelian factors are borne by chromosomes and 

 arranged in definite sequence within them. Difficul- 

 ties remain, but a theory which enables predictions 

 to be miade and verified cannot lightlv be disregarded. 



L. DONCASTER. 



The Conservation of Fuel. 



IN view of the importance of national economy in 

 our fuel reserves, it is not surprising to find that 

 Sir Dugald Clerk selected the subject of the con- 

 servation of fuel in the United Kingdom for the James 

 Forrest lecture which he delivered at the Institution 

 of Civil Engineers on April 20. The coal raised in 

 1913 was about 287-4 million tons, of which 189 

 million tons were retained and consumed here. The 

 total coal reserves at 2 per cent, per annum increase 

 will be exhausted in about 250 years, but fuel will 

 be so expensive long before that time has elapsed that 

 we shall be hard ^pressed to maintain the existing 

 population. A return to the agricultural civilisation 

 of 1750 would require the reduction of our population 

 to one-third. It is of the utmost importance to study 

 the engineering problems arising. 



A great part of the lecture was taken up in criticis- 

 ing the figures given by the Coal Conservation Com- 

 mittee. It will be remembered that this Committee 

 advocated the establishment of large turbo-«lectric 

 stations at about sixteen centres, and the covering of 

 the country with a network of mains capable of 

 supplying our whole power needs by electric motors. By 

 this scheme the Committee expected to save 55 million 

 tons of coal on power alone. Many competent elec- 

 tricians and capable motive-power engineers have the 

 gravest doubts as to the accuracy of the data pre- 

 sented, and as to the outcome of the ambitious scheme 

 advocated. The Committee adopted the figure of 

 5 lb. of coal oer horse-power-hour as the nresent 

 consumption ; Sir Dugald gave estimations arrived at 



NO. 2639, VOL, 105] 



by two different methods : one of 39 lb. per b.h.p.. 

 hour and another of 405 lb. per b.h.p.-hour. The 

 first value is based on a census of production data 

 corrected by allowing for steam production other than 

 for motive power, and for an error in total h.p.- 

 hours as determined by the Committee. The second 

 value of 4-05 lb. is estimated by considering the 

 average of many typical steam engines. Taking the 

 whole of the facts into consideration, and assuming 

 electricity in the" future to be used for the generation 

 of power and light only, then a reduction to 1-56 lb. 

 of coal per b.h.p.-hour would give a possible saving 

 of not more than 37^ million tons of coal per annuni! 

 The saving of 55 million tons exoected by the Com- 

 mittee is, in Sir Dugald Clerk's* opinion, based on 

 fallacious reasoning. 



The Committee in its report clearly intends also 

 to generate heat, and expects to do so with econom\- 

 superior to the existing systems of coal and gas com- 

 bustion. Sir Dugald went into the question of the 

 comparison of gas with electricity for "domestic heat- 

 ing, and arrived at the figure of 43-6 per cent, of the 

 heat used at the gasworks as the proportion which 

 the consumer receives at his premises; taking the 

 efficiency of the gas at 42 per cent., the final efficiency, 

 referred to the heat consumption at the gasworks, "is 

 43-6 X 0-42 = 18-3 per cent. Iri electric heating the con- 

 sumer receives 117 per cent, of the heat consumed in 

 the thermodynamic transformation at the super-station, 

 and using this with an efficiency of 59 per cent., the 

 consumer obtains in his apparatus 117 x o-59 = 6-9 per 

 cent, of the heat units consumed at the generating 

 station, .'\ssuming the gasworks to be abolished, and 

 electric generating stations to be expanded so as to 

 supply current for heat supply at the same generating 

 efficiency as for power, and taking all facts into con- 

 sideration. Sir Dugald estimates that the whole 

 assumed saving on power will be lost, and that &i-(> 

 million tons of coal per annum will be consumed 

 instead of 67-5 ; he therefore considers that the super- 

 stations will not justify their existence, that the 

 Government scheme is wrong, and that the sweeping 

 conclusions a;-rived at by the Coal Conservation 

 Committee are unjustifiable. 



Sir Dugald gives some methods of saving fuel which 

 are immediately applicable. Great changes are now 

 in operation throughout the gas industry due to the 

 adoption of the thermal unit standard for sale. In a 

 few years the majority of gasworks will deliver to 

 the consumer in the form of gas 75 per cent, of the 

 whole heat of the coal, and the improvements in gas 

 apparatus, etc., are so great that the efficiency of use 

 of the gas will rise from 42 to 55 per cent. He 

 estimates that a saving of 4-8 million tons of coal on 

 the present consumption will result from these 

 changes. On the assumption of the complete displace- 

 ment of coal in households by gas, we should use 

 onlv 17-1; million tons instead of 35 millions. 



Mr. D. Brownlie's figures for coal consumed in 

 boiler furnaces were quoted. If boiler attendants be 

 better trained, and masters take some pride in obtain- 

 ing best efficiencies, a saving of 4 million tons per 

 annum would result. Collieries consume about 17 

 million tons per annum in boiler furnaces at an 

 average efficiency of 55-5 per cent. If this be raised 

 to 75 per cent., the saving on this item would be 

 4A million tons per annum. 



The notion of the great gain to be expected from 

 very large steam turbines is held to be quite erroneous. 

 Even with the most modern plant an increase in 

 power per turbine from 10,000 to 100,000 kilowatts 

 only reduces the steam consumption from 9 to 8-5 lb. 

 per kilowatt-hour. A recent examination by Sir 



