3«l 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[Not. 



tiT»; views, and there arc ro eleyations of buildings, but a museum, as 

 it were, is formed of details so carried out, tliat working drawings 

 would be scarcely wanted in copying tlifse exani|ilc«. Tlie plates, 

 wliicli are filled as much ;is tliey can be, are designed simply to lielp 

 tlie arcliitecf, builder, and workman, and explain themselves so fully 

 lliat llie text is scarcely required. Indeed, llie beok, on inspection, 

 carriis willi it its own recommend ilion, and is likely to meet witli 

 such support as to ena( le the author to proceed with confidence in his 

 praiseworthy undertaking. 



A History of the Architecture of the Abbey Church of St. Alban't, 

 with especial Refennce to the Norman Slructure. Ey J. C. Bl'ckleb 

 and C. A. Buckler. London : Longmans, 1847. 



This is a work of such commendable industry, and of so much in- 

 terest, that we must reserve it for a longer notice in a future number. 



HIGH-PKESSUKK STl.AM. 



The greatest object remaining to he accomplished in navigalin? the ocean 

 by steam, is unquestionably the saving of fuel, and this, to any great extent, 

 can only be efiected by using high pressure steam expansively, by which 

 not only one-half ti{ the tonnage oecujiied at least will be liberated, but one- 

 half the cost of the fuel « ill be saved. Me net-d not expatiate upon the 

 immense iniporlancp of such a reducliun, both to the naval and commercial 

 marine of this ecainlry, particularly wlure distant depots have to be so 

 frequently rephnished, bcranye that can he duly appreciated by every 

 person practically experienced in steam navigation. But no sooner, how- 

 ever, is the proposition mooted, tlian a fierce fusilade is opened against 

 so dangerous an innovation, vvhicli dial is presumed to be,— as if any in- 

 herent property existed to render high-pressure steam more dangerous or 

 destructive than steam of low-pressure. This, however, results from pre- 

 judice rather than from calm and dispassionate reasoning; in the t'aee, too, 

 of daily experience and the successful operation of hundreds of locomo- 

 tives gliding over our iron roads at something like Ct) miles an hour, not- 

 withstanding the very high power employed, which marine purposes do 

 not require, — that it is really gratifying to read your judicious and perti- 

 nent remarlis in the case of the late explosion of the Cricket steamboat. 

 [see Journal, p. 330] 



With properly constructed safety-valves, to limit the pressure with cer- 

 tainty, placed bejond the control of the engineman or driver (which is a 

 matter of equal importance in both systems), high steam wdl prove as 

 safe, nay salVr than low-pressure, if generated in suitable boilers ; which, 

 ■we trust, we shall be able to show. \Ve are not aware if there exists any 

 collected record of the number of explosions which have occurred, distin- 

 guishing the class to which each belongs, together vviih the probable cause 

 and circumstances attending them, beyond the transitory and imptrfeet 

 accounts given in the news of the day; or we believe it would be founil, 

 that not only are the most destructive effects produced, but also that two- 

 thirds, possibly three-fourths, are occasioned by low-pressure steam, or by 

 boilers so denominated (see the frightful account of the explosion in the 

 newspapers of lo-daj — October the 7th — as detailed liefore the coroner at 

 Leeds). And what would have been ihe consequence if many low-pres- 

 sure marine boilers had been suljecled to the foul-hai'dy and reckless 

 treatment practised on hoard the '■ t'rieket.'"' Would they have resisted 

 one-half ttie tune those boilers did > — we piesunie to think not. 



Marine boilers of the usual form of construction and maguilude are the 

 worst to resist pressure ; and, therefore, in examining the comparative 

 safety of the two sj stems, we will assume that the boilers are of the same 

 form — viz. cylindrical (where the tension of the metal is most perfectly 

 applied), and the pressuie in one to be four pounds the square inch, and 

 that of the other to be fifty, while the thickness of metal in each shall be 

 in the exact ratio to the strain : thus, ninlliply the pressure by Ihe radius, 

 and divide the sum by 400 (equal to one-tenth of llie strength of the plate 

 for every eighth of iis tliickness), and the quotient will express Ihe thick- 

 ness in eighihs which the plates of each of Ihe boilers should contain. 



Thus, we have two boilers whose power of resistance in relation to their 

 contents are exactly equal ; hence, if the lifly pounds steam were to be 

 doubled, the pressure would not be one iota more dangerous than Ihe four 

 pounds sleaui being increased to eight, and riie icrsii ; consequently, in 

 relation to strength, one boiler is as likely lo explode as Ihe other : but 

 as neither is likely lo take a flight if duly supplied with water, and their 

 safely valves be in good Older-, we will proceed lo consider the result iu 

 case of neglect— liisl, with regard lo a deficiency of water, and next lo the 

 valves becoming fixed. With respect to a delicrent supply of water-, the 

 chance of an explosion would probably he pielly nearly equal, and so 

 would be the force, from the larger volume necessarily penl up in low- 

 pressure boilers; indeed, we are not aware that there is any distinction 

 observed in this particular, but in ellecl the low tleani may be assumed lo 

 be more disaslious from its scalding properly, as jou very properly 

 remark, than high-pressure. In respecl to Ihe safety-valves, we have 

 shown that each boiler is capable of resisting ihe doubling of the working 



pressure of its contents, or any other extent in the same ratio in an equal 

 degree. Now, it is quite possible for a low-pressure valve lo adhere lo its 

 seal so firmly as to resist Ihe additional four pounds per inch, and even a 

 much greater increase, ere an explosion ensue; but for a valve of a high- 

 pressure boiler lo resist an addition of Gfty pounds per inch without being 

 unseated, is scarcely within the bounds of probability. All boilers require 

 careful and efficient superintendence most unquestionably, and casualties 

 from neglect will somelinies occur without doubt; but under an equal 

 degree of supervision and skill in couslruction, we think we are justified 

 iu the conclusion that high pressure steam in regard to safety bas the 

 advantage. 



The quantity of fuel saved depends upon the just application of the 

 expansive principle : the usual practice is for the pressure in the boiler to 

 be constant, ami the amount of expansion varied by expansive gear, ac- 

 cording lo Ihe exigencies of the service. To prove thai this is an error, 

 we haveonly lo imagine a cylinder, say t'oirr inches long and one in diame- 

 ter, wiih steam of four pounds cut off at one quarter its length and allowed 

 lo expand lo four limes its volume, which will exert a mean force of two 

 pounds and a fraction ; this we vvil] assume lo be the minimum working 

 power of the engine. Now, if circumstances require the maximum power 

 lo be applied of four prmnds during the whole stroke, it is manifest that a 

 four fold amount of steam will be required, and expansion must be aban- 

 doned altogether to etl'cct it when its saving effect is most requisite, as the 

 largest amount of fuel is being consumed. Now, if we reverse these 

 functions, by making the amount of expansion constant, and work with a 

 rariahle pressure, it will be found that the steam required will be exactly 

 in the ratio of Ihe vvoik done; thus, if we raise Ihe pressure to eight 

 pounds, and cut oil" the steam as before, we obtain a mean of over four 

 pounds, with just double Ihe quantity of steam, iu&teail of quadruple as 

 above, and of course at one-half the expense of fuel. The pressures here 

 assumed for illustrating Ihe two modes of application are not those, of 

 course, which would be adopted iu practice, but ihe result would be the 

 same in effect if ihe maximum pressuie were sixty-five pounds above va- 

 cuum, and the minimum one-half Ihat amount, working with a constant 

 expansion of eight or ten limes its original volume. 



Now Ihat competition is so strong in rates of speed, every degree of 

 pressure is rniployed and steam generated in all kinds of boilers, suitable 

 or unsuiiable ; the temptation is so greai lo run dangerous risks for the 

 sake of victory, that some power of control is become absolutely necessary 

 — a matter, however, of no very difficult accomplishment, thorrt'.h it might 

 be opposed by the jiroprietors, possibly, as exposing the secret of Ihe doings 

 in Ihe engine-ioom, with regard to Ihe real working pressure ; but that is 

 a matter of no weight, nor can it be honestly objected to or denied. We 

 would suggest, Iheu, that a competent person should have the power to 

 inspect all sleamhoats periodically, as lo the fitness and condition of Ihe 

 borler-s iu I'elatiou to their working pressure, and lo see the following pre- 

 cautionary checks adopted — viz.: One safety-valve, at least, on each 

 boiler, placed bejond the contrid of the engineer, except as to having the 

 power of lifting it occasionally, lo insure its duly operating ; or by a slight 

 easement efiected at regular iniervals by Ihe engine itself, but no power of 

 adding weight. Next, Ihat two graduated gages be fixed in one case 

 above rieck ; one showing the pressure of steam in the boilers, and Ihe 

 other the level of the water and the excess or deficiency in either case from 

 the fixed working points on the scale- 1 hese gages lo be open at all limes 

 for iospeciiou to every person on board, and minutes made in the log at 

 regular intervals in sta-going steamers, particularly during the night, 

 stating Ihe height of Ihe water and pressure of steanr. I'be sound work- 

 ing coniiition of these gages to be maintained at all times, and cases of 

 neglect, or tampering with Ihem in any manner, lo be visited by a severe 

 fine — perhaps line and imprisonment, where so many lives are endangered, 

 which would at once put an end to ilie reckless tampering with the pres- 

 sure, and insure careful alteutiou to the supply of water, and consequently 

 safely to all on board. 



C. 

 London, October 7, 1847. 



FULGURITES AND FULMINAKY TUBES. 



We have found in a French periodical some remarks on the action of the 

 electric fluid when striking Ihe ground, which do not seem lo have attracted 

 much attention here, and which have led us to look into the sulject. It is 

 observed that in the beginning of the last century, a hollow tube was dis- 

 covered, which formed branches, in the sandy plains of Silesia. This tube 

 was placed in a museum under Die name of an "arborescent fossil." Some- 

 what later, similar tubes were found in the neighbouihood of Taderborn, 

 Dresden, and Munster, likewise in Cumberland, in Hungary, on ihe dunet 

 near lloriieaux, and on the plains of Bahia in Brazil. M'e do not remember 

 any specimens of this kind in the British Museum, although there is an ex- 

 tensive collection of meteoric stones in the mini ralogical ilepartnient. Ibis 

 suggests the propriety of a separate collection, which should include me- 

 teorites, fulgurites, minerals and vegetables affected by electric action, vol. 

 canic substances, &c. These would extend our knonleilge of new branches 

 of science, those of meteorites, geological action, and coralline growth. 



All the localities in which fulminary tubes are found, although far apart. 



