1845.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



275 



of h becomes smaller; suliject only to a limit similar to that ia the 

 first question. Since the pressure in the cylinder can never be greater 

 than that in the boiler the maximum eflect will be produced by giving 

 h such a value that 



Hence we have for the greatest useful value of A 



. = ,'. 



where the evaporation is equivalent to m cylinders-full of steam of 

 the pressure p per minute. Here p is an unknown quantity, but m is 

 known, because the velocity of the engine is supposed to be known. 

 By ascertaining, therefore, the cubic. il content of the cylinder and re- 

 ferring to M. de Farabour's tables, for the relation of the volume of 

 steam of any pressure to the water from which it is generated we shall 

 be able to ascertain p. 



To take an instance, let us suppose the evaporation of an engine 

 Buch as that which M. de Pambnur takes as tin- average, namely that 

 J cubic foot of water is tranferred to the cylinder in steam each 

 minute. Also let the number of revolutions of the wheel per minute 

 be lltj. (This corresponds nearly to a s|)eed of 20 miles an hour, the 

 driving wlieel being G ft. over.) The engine fills each of its cylinders 

 twice in each revolution : the number of cylinders-full of steam per 

 minute will therefore be 4lJ4. Suppose the capacity of each cylinder 

 Jiy cubic foot. Then "m cyhnders-full of steam of pres'-ure ]j" become 

 equivalent to 4 IT'O cubic feet of steam of pressure p. But this steam 

 is supplied by J cubic foot of water. The steam would have, there- 

 fore, 55li times the volume of the water which produced il ; and by the 

 tables it appears that this relative volume corresponds to a pressure of 

 501b. per inch, or 35 lb. effective pressure, which is th.erefore the value 

 of p. Hence, if the effective boiler pressure be 50 lb. per inch the 

 formula 



r P u I 35 



i z= fr o becomes 4 := -— a 

 F 50 



or the greatest useful lead of the slide is in this case given by cutting 

 oifthe steam at .j^ths of the stroke. 



It will be seen from (D.) that the load would in this case be in- 

 creased in the proportion 



1 : 1 -f log ^ or 1 . 1-35G 

 or for the same amount of fuel and the same velocity the load may be 

 increased about jy''* ^Y the lead of the slide. 



I believe that I have now considered all the princi|)al cases of the 

 question of the lead of the slide, though for brevity some points are 

 omitted to which I shall recur hereafter. As far as I am aware the 

 question, notwithstanding its importance, has never been accurately 

 discussed. Tbis may appear a strange assertion, but the reader will 

 not deem it incredible, if he agree witb me in considering M.de Pain- 

 bour the great authority in matters relating to the theory of the steam 

 engine, and also agree with me that in the present instance M. de 

 Patnbour is in error. Tredgold, I believe, discusses the question 

 without reference to the rate of evaporation in the boiler : if so, I need 

 «carcely say, after the laws laid down above, that I consider his rea- 

 »oning totally fligitious. I confess that the errors which abound in 

 his works have long since led me to estimate his physical tbeories 

 very lowly. The problem of the steam engine is one which for its 

 importance to the welfare of mankind, for its interest, and above all 

 for the i.raclitude of which it is susceptible, deserves the energies of 

 the profoundest mathematicians, but they have strangely neglected it, 

 «nd it has consequently been approached by the veriest sciolists, 

 whose erroneous reasonings have only widened the breach between 

 the engineer and the philosopher. To this remark De Pambour is 

 indeed an illustrious exception; but where are his fellow labourers ? 

 The investigation which I have just m ide, for example, ought to have 

 devolved into far other hands than mine. I have striven to render it 

 at least not inaccurate, but it ought to have been undertaken by those 

 who could have given it a value much higher than this negative qua- 

 litication. 



H. C. 



REVIEWS. 



tellers on the Ujiheallhy Condition of the Lower Class of DmUiiigs, 

 witn an Jipi^endtT, containing Plant and Tat/itn. By the Rev. 

 CilAUi.ES (jutDLiiSTONE, A.M., Ri.ctor of AUWrley Cheshire, — Long- 

 man, 1S15, 8vo. pp. 92. 

 T.ie ianatury condition of our large towns has for some time past 



occupied a large share of public attention, and deserves to occupy a 

 much greater. The abstract of the second report of the Health' of 

 Towns' Commission, which we gave in our last number, presents a la- 

 inentable and alarming picture of the degradation of the lower classes 

 in manufacturing towns. While we are hugging ourselves with the 

 pleasant conceit that the schoolmaster is abroad, that science is rapidly 

 advancing, and that railways and electric telegraphs are fist bringing 

 us to a species of intellectual millenium we seem to forget that for 

 the present, at least, all our improvements principally affect the upper 

 and middle classes of society. The vice and squalid debasement of 

 the manufacturing population, as exhibited in the Commissioners' Re- 

 port, can scarcely have been paralleled, and, we are bold to say, has 

 never been exceeded at any period of our social history. It is a'posi- 

 tive fact that in many places education has rapidly retrograded, in- 

 st.ad of advancing. It appears from the Report of theRegistr ir- 

 Gcneral, that out of every hundred couples married in LancisUre, 

 during the last few years, "only 12 men and 8 women were able to 

 sign their names," whereas Mr. Coulthart has shown that eighty years 

 ago 54 men and 17 women out of a similar number wrote their names. 

 Such statistics as these furnish a far more forcible picture of the de- 

 plorable condition of the poor in populous districts than the most elo- 

 quent rhetoric could supply. The inseparable companions of general 

 Ignorance are these— Poverty— Squalor— Disease— Crime. If the 

 reader will examine the ollicial report, or still better, obtain informa- 

 tion by his own personal inspection, he will be able to trace each of 

 these four consequences of ignorance, with terrible distinctness, in the 

 social condition of the lower class of labourers and artizans. The 

 latter of these consequences is a subject too distasteful to be insisted 

 upon in more thav. general terms; be it enough to explain that it is 

 but too certain that the promiscuous herding of the poor in crowded 

 tenements, is a most fruitful cause of vice, which violates the purest 

 ties of nature. These violations of the laws of humanity, it seems to 

 be now ascertained, are vastly more numerous than the reports of the 

 assizes would lead the public to suppose, and are almost inseparable 

 from the present arrangement of the tenements of the poor in populous 

 places. 



"The sanatory condition of the poor is however the more immediate 

 subject of the excellent and most philanthropic pamphlet before us. 

 The writer has chosen for his motto the following forcible passage 

 from the writings of one whose affectations of language cannot whoUy 

 obscure the beauty of his thoughts — Carlyle. 



Health is a great matter, both to the possessor of it and to others. On 

 the whole, that humorist in the Moral Essay was not so far out, who deter- 

 mined on honouring health only ; and so, instead of humbling himself to the 

 high-born, to the rich and well-dressed, insisted on doffing hat to the healtliy : 

 coronctted carriages, with pale faces in them, passed by as failures, miserable 

 and lamentable ; trucks with ruddy-cheeked strength dragging at them, were 

 greeted as successful and venerable. For does not health mean harmony, the 

 synonym of all that is true, justly ordered, good? is it not, in some sense, 

 the net total, as shewn by experiment, of whatever worth is in us ? The 

 healthy man is a most meritorious product of nature, so far as he goes. A 

 healthy body is good ; but a soul in right health, it is the thing beyond all 

 others to be prayed for; the blessedest thing this earth receives of heaven." 

 Mr. Girdlestone's pamphlet is professedly founded on the first Re- 

 port of the Health of Towns' Commission. He first of all brings proofs 

 of the accuracy of the inquiry, by explaining the manner in which it 

 has been conducted, and then enters upon the several subjects of un- 

 healthy influences, defective drainage, insufficient supply of water, 

 &c., but as we have already devoted much space to the subject, we 

 can only avail ourselves very partially of the valuable information 

 which he has collected. We have selected the following passages 

 from the chapters on Drainage and Ventilation. 



We are daily bringing into our streets and our abodes both water from 

 springs, and wells, and rivers, and also various other matters, liquid and solid, 

 for food and for many other uses ; of which matters, a very large amount', 

 and ultimately the whole, or nearly so, becomes refuse, and must somehow 

 b- got rid of. Now a perfect system of sewers is adapted for the di^pj-al of 

 all such refuse matters, whether liquid or solid ; the one helping to tioat 

 away the other, and the rain as it falls washing all out clean. And such a 

 system, to be perfect, must clear off every kind of refuse out of the precincts 

 of the house and of the town, before it has begun to decompose and putrifv ; 

 and then the town atmosphere would not only be as drv as that of the coun- 

 try, hut as free from everything that is offensive and injurious, as far at least 

 as this refuse matter is concerned. Hut if there be no etfijient public seners 

 if the refuse be merely put out of sight in cesspools and dust bins or in 

 sewers, which, for want of a proper fall, are full of stagnant filth, and act as 

 extended cesspools; if tliere be no drains from each house into the public 

 sewers, and no traps or valves, or fla)is, at each opening of sewer and of 

 drain ; if there be no good pavement, nor any well formed roadway imper- 

 vious to moisture; in such a case, and in propoition as these several points 

 have iQ any case been neglected, there, not only the rain, but a 1 ih- water 



