322 



THE CIVIL ENGINKER AND ARCHITECTS JOURNAL. 



[OCTOBKH, 



"Fig. 3 is a section representiiiff aboys'and girls'school ventilated 

 (except as regards the windows) in a satisfactory manner; a a are 

 the fresli-air openings; h h. pipes for heating; '■ r, gratings for 

 entrance of frcsli warmed air; </ rf, openings for foul air, leading 

 into a trunk e, whence it is drawn down the shaft/ by the rarifying- 

 fiirnace y, whence it is discharged up the shaft A into the 

 atmosphere. 



"This arrangement of a rarified shaft, continued down to the 

 ground for the purpose of obtaining a quick drauglit by a heated 

 colunin, and requiring a down shaft to connect the ventilating 

 trunk, from tlie top of the building, with its lower end, sothattlie 

 foul air may enter it belovv the fire, is the same that has been 

 ado]ited, at very great cost, by Dr. Ileid, in the new Houses of 

 Parliament. There is a complexity and expense about this arrange- 

 ment which would seem to be needless. The drawing down to the 

 ground-level of the whole of the vitiated air of the building, and 

 then sending it up again; the cost of connecting the main down- 

 shaft with tlie up-shaft, which circumstances may require to be at 

 a considerable distance; and the trouble of forming air-tight 

 connecting-flues to convey the vitiated air from numerous rooms 

 to one main down-shaft, to say nothing of the double space and 

 materials occujiied by the two shafts, would render tliis plan, in 

 numerous cases, imjiracticable. To overcome some of these diffi- 

 <ulties, the fire has, in many cases, been provided for at the roof- 

 level ()' fig. 3), thus relin(piisliing the down-shaft and the lower 

 IC'.rt of tlie up-shaft, and so far has been an improvement; but in 

 laany cases the trouble of carrying up fuel and ascending to 

 attend to the fire was too great, and the ventilation w as, therefore, 

 uncertain. The best mode of effecting forcible ventilation by a 

 shaft doubtless is, to adopt the last-named arrangement; substi- 

 tuting gas rarifiers for a furnace, as shown in the cburch. (Fig. 1.) 

 By bringing the pipe which supplies gas to the burners to some 

 accessible point near the ground-floor, with a stop-cock at that 

 point, the handle of which should work in a graduated quadrant, 

 the ventilation can be regulated from below with great ]irecision. 



" U'indov.-ventilation of a kind very fre(iuently adopted in 

 churches and schools, has been introduced into tliis figure (A- fig. 3), 

 not with a view- to represent it as part of Dr. Reid's system, but 

 to illustrate its bad effects, either where it is the sole provision 

 made, or wliere it is used in combination with a better process. If 

 it be the sole provision made, and the room be heated by a fire- 

 jilaceor stove, to 60', a downward rush of air at 10' (should that 

 low temperature happen to prevail outside at the time), will play 

 ui>pn the heads of those near it. If it be in force, as in the figure, 

 simultaneously with proper means of introducing fresh warmed 

 air, its force will be modified, and partially deliected upwards, 

 towards the egress openings; but whatever C(dd air thus enters, is 

 so much deducted from that which ought to have entered warmed, 

 thriuigb the proper channel c." 



We may observe, that Mr. Walker has been largely engaged at 

 Manchester in the construction and adaptation of stoves, and that 

 he has had considerable experience in many practical applications 

 of ventilation. 



Suggestions for a Ac'w Street through the City of London, with a lead- 

 ing Aqueduct Sewer. By Nathaniel Beard.more, M. Inst. 

 C.E. London: Weale, isio. 



Mr. Beardmore proposes a very extensive system of street im- 

 provement and drainage. One part of his plan is to do away with 

 \Vestminster and Charing-cross Bridges, and to construct a grand 

 bridge leading from Charing-cross to the Waterloo-road. Another 

 ))art is a street from Temple Bar, across Bridewell, south of St. 

 I'aul's Churchyard into Kastcheap, and thence by Crutchedfriars 

 and Great Alie-street to the Commercial-road. Coupled with this, 

 he proposes to carry a grand sewer through the metropolis, from 

 Bayswater to Barking Creek. 



li )yal Agricultural Society's Prize Model Cottages. By Hexby 

 GoDDARD. London: Dean. 

 -Mr. Goddard, an architect of Lincoln, gained the first prize for 

 model cottages offered by the Royal Agricultural Society of Eng- 

 laiul, aiul we presume that his designs were the best of those pre- 

 sented for competition ; but we must say we have seen many designs 

 which are more picturesque, and with better arrangements. 



ON COOLING THE ATMOSPHERE OF ROOMS. 



Sir — I was very much pleased with the description given in 

 your last number, of the very ingenious and simple machine for 

 cooling the atmosphere of rooms. Among the many excellencies 

 of the apparatus, not the least, 1 think, is the similarity between 

 t)ie means employed in it and the operations of nature constantly 

 producing similar effects — I mean the change of temperature by 

 chanse of density. It is, indeed, an extraordinary thought, that 

 the changes of temperature observed at different heights in our 

 atmosphere may be accounted for by the fact of rarified air having 

 a capacity for heat, increasing with its rarifaction, and that the 

 same air which, made dense by the pressure of the atmosphere, 

 feels so warm at the surface of the ground, may, wafted to some 

 hill top, and thus freed from some part of the pressure, become 

 the coiding breeze; and anon, mounting still higher, may take its 

 place among the regions of eternal snow. It appears to me that 

 the similarity existing between the means employed in the appa- 

 ratus, and this process in nature, forms the very best guarantee of 

 its effecting the object desired in the most suitable manner, as the 

 parallel between the two operations exists throughout. 



It appears to me, however, that some explanation of the cause 

 of the increase of the temperature of air on compression would 

 render the account of tlie apparatus more intelligible to the 

 geiieral reader, as it might create misunderstanding on the subject 

 merely to say that air increases in temperature on compression, 

 and diminishes on expansion; the fact being, that on compression 

 the same quantity of heat exists in the air as did before compres- 

 sion; but this increase of density diminishing its specific heat 

 (/. e. the quantity of heat required to keep it at its former tem- 

 perature), the amount of heat it possesses above this must make 

 itself sensible, and raise the air to a higher temperature; while, on 

 the other hand, when by being rarified, or being allowed to expand 

 itself in a larger space, its specific heat being increased, the quan- 

 tity it possesses is unable to maintain its temperature, and it 

 consequently is diminished, though neither change of temperature 

 is in the same ratio as the compression or expansion. 



I should scarcely think it possible that the objection anticipated 

 by the inventor — viz., that the cooled air would be found unplea- 

 santly moist, could occur. For, supposing the air to be lowered to 

 the required temperature, it would be able to hold in suspension 

 an amount of moisture in accordance with its temperature; and, 

 of course, any attempt at condensation of moisture must be made 

 by removing some portion of the heat of the vapour. As Dr. 

 Lardner, in his 'Treatise on Heat,' observes (in speaking of the 

 liquefaction of vapour by compression), that without an actual loss 

 of heat having been sustained by the vapour, it would be impossible 

 to imagine the condensation of any portion of the vapour into a 

 li((uid, as such condensation must be effected by the subtraction of 

 all the latent he;:t which maintained the liciuid in a vaporous form. 

 ]5ut should it be found desirable to lower the temperature of the 

 air more than cjuld be effected (with air subjected to the amount 

 of pressure stated as that best adapted to the purpose) by water 

 of the temperature of 100°, or should it be found impossible to 

 procure water of so low a temperature, I should think (as me- 

 chanical power must be used for condensing the air) that the mere 

 evaporation of such water as can be procured — effected as described 

 below, in a space approaching to a perfect vacuum in proportion to 

 the degree of cold required, the vapour arising from the water 

 being constantly removed, in order that its tension might not 

 prevent the furtlier evajioration of the liquid — would amply serve 

 the purpose intended. 



This effect might be obtained in the manner shown in the accom- 

 panying sketch, w here A, B, C, D, is a cylinder, with openings at 

 the sides to connect the pipes containing the air with the air 

 chamber in the cylinder by spigot-and-faucet-joints. A\'ater is to 

 be placed in the cylinder, so as completely to cover the air chamber 

 E, E, E, as shown by the level F, F. In the cylinder, a piston G 

 works. This might be made perfectly air-tight with ordinary 

 hemp packing, tlie upper plate of the piston being merely provided 

 for tlie purpose of screwing down the hemp as might be found 

 necessary, and being formed with large openings in it, as shown in 

 the section; while in the lower plate a valve H, is placed, which 

 might be loaded in a proportion relative to the tension of the 

 vapour to be raised from the water. Thus, supposing the required 

 temperature of the water to be 50^. The tension of the vapour of 

 water at 50' is 0'375 of an inch of mercury; and as the amount of 

 the pressure of the atmosphere (15lb. on the square inch) is 

 equivalent to 30 inches of mercury, it follows that tlie tension of 

 the vapour of water at 50° is equal to an 80th part of the weight 



