November i, 191 7] 



NATURE 



167 



of the shop engine and its temporary substitute, 

 the intense concentration of considerable power 

 into very small space which the introduction of 

 this engine brought about. 



Although in a recent report by the British 

 Commercial Gas Association there is given infor- 

 mation as to the weight of steel cylinders for 

 containing gas at pressures at 20, 25, and 120 

 atmospheres, there is little reason to expect 

 supplies of these containers to be available in 

 any quantity likely to affect the problem ; even 

 if they were, these figures show that the 

 storage capacity for the equivalent of 4 gallons of 

 petrol would weigh Ijetween 1000 lb, and 2000 lb. 

 (depending on the pressure). So that on dead 

 weight alone they would be at a great disadvan- 

 tage compared with the atmospheric pressure, or 

 "Beeston," system. 



The illustration shows the vehicle which is 

 stated to have been the first to be run on this 

 system. The movement has since spread very 

 rapidly, and reference to the technical Press 

 shows more than a dozen firms making the fabric 

 containers and above a hifndred firms offering to 

 fit them. H. E. Wimperis. 



A NATIONAL FOOD POLICY.-^ 



THE greatest war of all time is slowly but surely 

 having a bound set to its ravages by the 

 limitations of the productive effort of the world's 

 agriculture. The steady drain of man-power, 

 increasing difficulties of transport, and unfavour- 

 able climatic conditions have all combined to cur- 

 tail the world's food supplies, whilst in many 

 countries the spectre of famine begins to loom 

 ominously in the distance. Few nations have fared 

 better in this respect than ours, but our difficulties 

 are steadily increasing, and there is widespread 

 anxiety as to the exact position at the moment 

 and our prospects for the near future. What is 

 our normal margin of safety ? How do we stand 

 to-day? How can we best avoid a worse condi- 

 tion? Such are the questions to which all would 

 have an answer, though few reaKse how difficult 

 it must be to provide. It demands the combined 

 skill of the statistician, the physiologist, and the 

 agricultural expert, and the fortunate combi- 

 nation of these qualities in his person thus confers 

 upon the estimates and conclusions of Prof. Wood 

 a title to consideration which probably none other 

 could claim. 



The report of the Food (War) Committee of the 

 Royal Society (Command Paper, Cd. 8421) has 

 previously indicated that our pre-war average food 

 consumption, as measured by its work-producing 

 power, was about 15 per cent, above the level 

 commonly accepted by physiologists as adequate 

 for the maintenance of complete efficiency. In 

 view of the increased proportion of the population 

 now engaged in strenuous work, this margin would 

 'doubtless be no more than 5 to 10 per cent, to-day, 

 even were supplies of food no less. The report 

 further showed the predominating position of 



"The National Food Supply in Peace and War." By Prof. T. B. 

 Wood. Pp. 43. (Cambridge IJniversity Press.) Price 6rf. net. 



NO. 2505, VOL. too] 



cereals and meat in the national dietary. Cereals 

 alone contribute more than one-third of the work- 

 producing power of the diet of the average " man," 

 whilst in the diet of the manual labourer the 

 proportion will often be nearer two-thirds. Bread 

 and meat together account for more than one- 

 half of the work-producing power of the nation 

 as a whole. 



If our margin of possibility in food economy 

 is but this 5 to 10 per cent., it is obvious that our 

 war food policy must embrace more than an anti- 

 waste campaign, urgently desirable though that 

 may be. The main problem is to secure the bread 

 supply. Unfortunately, the two most obvious 

 solutions, increased importation and greater home 

 production of wheat, are not easy of attainment 

 and become progressively more difficult as the 

 war continues. It does not seem likely that the 

 utmost effort in these directions will produce any 

 very considerable immediate result. Prof. Wood 

 sees a more practicable solution in the diversion 

 of large quantities of bread-corn and other food- 

 stuffs from animals and industry to human con- 

 sumption. Of our pre-war annual supply of 

 seventeen million tons of grain of all kinds, little 

 more than five millions served directly for human 

 food, whilst animals consumed above nine millions, 

 the rest going for seed, for brewing, distilling, 

 and other industries. Basing his argument upon 

 the fundamental wastefulness in time^ of scarcity 

 of the conversion of bread-corn into meat, as 

 illustrated by the fact that the most efficient 

 of meat-producing animals, the pig, produces no 

 more than i lb. of dry human food for 12 lb. of dry 

 grain consumed, and after reviewing carefully the 

 significance of each of the cereals for animal feed- 

 ing, Prof. Wood concludes that fully three and 

 a half million tons of cereals might be transferred 

 from animal fodder to human food, with a result- 

 ant net gain of two and three-quarter million tons 

 of dry human food, and a reduction in the necessary 

 import of grain for the year 1917-18 of three 

 million tons below the pre-war figure. 



After a detailed estimate of the fodder of all 

 kinds likely to be available for live stock. Prof. 

 Wood concludes that, broadly speaking, despite 

 the diversion of fodder suggested, it will be pos- 

 sible to maintain our live stock, but it will not be 

 possible to produce so large a total output of 

 growth, meat, milk, and work. Full provision 

 for work and milk must, however, be regarded as 

 indispensable, so that the brunt of the shortage 

 must be borne by the meat-producing stock. Pigs 

 and poultry are the most economical converters 

 of fodder into animal food, but, unfortunately, 

 their diet consists largely of grain or grain pro- 

 ducts which can no longer be spared. Sheep are 

 fairly economical food-producers, consume mainly 

 grass, hay, and roots, and produce wool as well 

 as food, so that they may certainly be encouraged. 

 Beef production, however, as normally carried on, 

 is a very wasteful process, owing partly to the 

 slowness with which ordinary cattle mature, and 

 partly to the extreme to which the fattening pro- 

 cess is commonly carried. By extending the use 



