172 



NATURE 



[August 5, 1909 



tliat Ihi- less the ratio of cooling surface to volume the 

 less the proportionate cooling loss, and therefore the greater 

 the amount of thermal energy converted into work. 



Engines that have "pockets," that is, cavities in their 

 walls, in which to contain ignition plugs or valves are 

 known to be less eflicicnt than those that have not.' On 

 the other hand, it must not be forgotten that althouc^h 

 this loss of efficiency exists, it is at anv rate partly com- 

 pensated for by the greater flexibilitv of the engine It 

 has been _ found, particularly in motor-car engines, that 

 pockets have a very useful eflect in enablin« verv 

 variable mixtures to f5re. The ignition plug is placed 

 in a pocket so that, even when the mixture is a very 

 poor one, there will be sufficient local "richness" in its 

 neighbourhood to start an explosion which, once started 

 proceeds throughout the mass of the gas. Another 

 fact_ which may have the result of increasing " pocket- 

 ing IS the recently measured temperature limit for pre- 

 ignuion. Trof. Hopkinson has found that surfaces below 

 700 C. will not cause pre-ignition, whilst those above 

 may do so-if above 750° C. they are prettv sure to do so. 

 .\ow the surfaces most likelv to rise to su'ch temperatures 

 are those remote from the cooling water in the jacket 

 ihe projecting end of an ignition plug is such a surface' 

 and when exposed to the full heat of the explosion, as it is 

 when the plug is not pocketed, pre-ignition niav well occur 

 1 lot. Hopkinson has shown also that when onJe a point of 

 metal gets hot enough to cause pre-ignition, the verv igni- 

 tion of the flame in its neighbourhood will tend to cause the 

 temperature to rise still higher, so that the phenomenon 

 grows , on itself and persists. It is not everyone w^ho is 

 moved, however, by such considerations, and w^e have latelv 

 seen in the design of the new Daimler engine a clearlv 

 expressed intention to avoid pocketing and its consequent 

 loss of efhciency without any apparent fear of introducing 

 other features much less desirable. It is onlv fair to sav 

 however, that this engine is still on its trial, the ideal plan 

 would appear to be 10 pocket the ignition plug but not 

 the valves, and so combine the good features of both 

 systems. 



This frank abandonment of the highest possible efficiency 

 by those \yho use pocketed engines brings us naturallv 

 to the consideration of thermal efficiency and the laws that 

 regulate it. One may say at once that the theorv of the 

 internal-combustion engine has, until latelv. been in a 

 chaotic condition. The standard of efficiencv for gas engines 

 lad down by an influential committee had been found 

 ideaTr""-' *T,?' ""satisfactory as giving an impo s"b"v 

 ideal figure. That such remarkable progress in invention 

 a^nd mechanical perfection should haveVne on Tide 1. "sfde 

 with this uncertainty as to the true standard of perform- 

 ance has often struck observers with astonishment. The 

 considerable scale of the practical side of gas-en<.ine 

 development is illustrated bv the fact that of one well- 

 ^ha7L"■;n^"' d^'^'-^^t-g gas engines alone, no flwer 

 than 247 eng nes of an aggregate output of 30S 000 b h p 

 have been built or ordered during the last six ve.ars Thk 

 corresponds to the large figure of more than ,0,000 bh p 

 per year for only one of the manv firms engaged on the 

 work. At the moment the total capacity of gas engines 

 .n use must be well over 2,000,000 h.p., and of n^etrol 

 engines much more than ,,000.000 h.p.^ makin« n^o ° 

 of more than 3 000,000 h.p. in internal-combus,io,r eng nes 

 Ihese are striking figures. Some of these engines^ and 

 plants work with solid fuel and some with Tiquid It 



r^iseT' M ?°'f"^''^' u^™" ^'-'^ '■' considered d'Tirabl 

 to use liquid fuel to the entire exclusion of anv other 

 The present output of petroleum over the whole word; 

 onb 20,000,000 tons, a very small figure compared with 

 the yearly consumption of 800,000,000 tons of coal 

 Lnless, therefore, fresh supplies of oil'are discovered, there 

 which "" development of the internal-combustion ^n^ine 

 altogeth" ' "' '" """" '""' ■•''P'--'^'"^ -'■<) f-I 



to '"deal" wTth''?. "^^ J'" '°i'°^^'- "^-^ a""^"-- '"'""ds 

 to deal with the problem of efficiencv, takine- into 



H. n. WlMTERIS. 



N-Q. 2075, VOL. 8ll 



CONTINUATION SCHOOLS AND NATIONAL 



EFFICIENCY.' 

 /V .\10NG the numerous problems now confronting 

 English educational administrators, probably the 

 most urgent is that discussed in the valuable and ex- 

 haustive report on attendance at continuation schools 

 recently issued by the Consultative Committee of the 

 Board of Education. To some extent the report covers 

 similar ground to that traversed in the educational sections 

 of the ivlajority and Minority Reports of the Poor Law- 

 Commissioners, arriving at almost identical conclusions. 



Ihe essential features of the problem are as follows: — 

 Under the existing Education Acts, children must attend 

 school from their fifth to their fourteenth birthdays, subject 

 to certain exemptions (prescribed by local bye-laws) during 

 the last three years of the school period. Local education 

 authorities may grant (a) total exemption from school 

 attendance at eleven years of age to children engaged in 

 agriculture, (b) full-time or half-time exemption, or both, 

 10 children between twelve and fourteen. The " leaving 

 age " is generally twelve or thirteen. Full-time attend- 

 ance at a day school until fourteen is now compulsory over . 

 areas comprising about 22 per cent, of the populat'ion of 1 

 England and Wales. The committee estimates that in the 

 year 1007, the latest year for which full statistics were 

 available, there were about 211,000 children under fourteen 

 years of age who had obtained full-time exemption from 

 day-school attendance. Of these, only 40,500 were attend- 

 ing evening schools in the year 1906-7, ' leaving 170,500 

 children between the ages liientioned not attending anv 

 form of week-day instruction. Further, the estimated 

 population of England and Wales between the ages of 

 fourteen and seventeen is 2,022,300. After deducting from 

 this the number attending elementary, secondary, technical, 

 or evening schools, it is estimated' that nearly 1,498,000 

 (or approximately 74 per cent.) boys and girls between 

 the ages of fourteen and seventeen are not receiving anv 

 form^ of scholastic instruction. We have therefore, about 

 1,(168,500 boys and girls from twelve to seventeen years 

 of age whose formal education has entirely ceased for the 

 time being. Recent inquiries in London and Glasgow 

 render it highly probable that a very large proportion, if 

 not the majority, of these boys and girls, if in wage- 

 earning occupations, are employed in purely mechanical 

 work of a monotonous, uneducational character, of no 

 industrial value when the child becomes an adult. 



Under these conditions the education, such as it is, 

 given in the elementary school is being rapidly forgotten. 

 The boys and girls are almost entirely exempt from 

 parental control ; they are falling victims to the prevailing 

 passion for cheap amusements and to the attractions of the 

 streets. Any slight gleam of intellectual aspiration which 

 may have been aroused in the elementary school is rapidly 

 being extinguished. The enormous sums spent by the 

 State upon the elementary education of these young people 

 are almost entirely waste'd. .All that remains' is a certain 

 facility in reading, writing, and verv elementary arith- 

 metic. Even if the boys are definite'lv apprenticed to a 

 trade, matters are not much better. 'Under the present 

 industrial _ conditions, involving the minutest possible 

 specialisation in the works, the employer cannot possibly 

 afford, even if he wishes, to give the boy the all-round 

 training which was given by apprenticeship under the older 

 industrial regime. Industry now requires, in addition to 

 manual dexterity, a general industrial knowledge and a 

 trained intelligence which will enable the worker to adapt 

 himself to ever-changing industrial conditions; but this 

 know-ledge and training are not now given bv apprentice- 

 ship. Hence, an education outside, but concurrent with, 

 the workshop is essential. A further important factor is 

 that even if a boy be apprenticed to a skilled trade, he 

 IS generally not taken on until about sixteen years of age. 

 The intermediate years, between leaving school at thirteen 

 and commencing apprenticeship at sixteen, are usually 

 spent in " blind alley," uneducational occupations such as 

 that of errand boy, van boy, messenger, &c. 



For many years to come the formal education given to 



1 R'port of ihe Consultative Commiltee of the Poard of Education on 



Attendance rompukory or otherwise, M Tortinns'lon Schook. Board of 



Educntion, White Paper. Cd. 4757. (London : Wyman and Sons.) Price 



IS. 6ir. ' 



