1845.1 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



ei 



landings of the plates, and superinducing an over-beating of the plates by 

 preventing a free access of tlie water to tlie metal. 



Then follows, with cxtriicts, some remarks on Mr. Parkes' table of 

 experiments on steam boilers, )mblislicil in the Transactions of the 

 Institution of Civil Engineers, and also Mr. Wicksteotl's experimental 

 enquiry, both of which have already occupied tlio pages of our Journal 

 at the time they appenred. It then proceeds with some observations 

 on tlie strength of boilers, giving some tables on the tenacity of iron 

 and copper; it would have been highly desirable in this case if the 

 authorities were given. From the observations on the strength of 

 boilers we take the following: — 



The difference in strength between strips of iron cut in the direction of 

 the fibre, and strips cut across tbe grain, was found to be about C per cent. 

 in favour of tbe former. Repeated piling and welding was found to increase 

 the tenacity and closeness of tbe iron, but welding togetlicr diftcreiit kinds of 

 iron was found to give an unfavourable result ; rivetiing plates was found to 

 occasion a diminution in tbeir strength, to the extent of al)out one-tbinl. 

 Tbe accidental over-heating of a boiler was found to reduce its strengtbfrom 

 65,000 lb. to 45,OnO lb. per square inch. Taking iuto account all tbcse con- 

 tingencies, it appears expedient to limit tbe pressure upon boilers in actual 

 use to about 3,0001b. per square inch of iron ; and in cases where tbe shell 

 of the boiler does not ati'nrd this strength, either stays should be introduced, 

 or the pressure within tbe boiler should be diminished. Tbe application of 

 stays to marine boilers, especially in tliose parts of tbe water spaces which 

 lie in the wake of tbe furnace bars, has given engineers much trouble ; tbe 

 ^ plate, of which ordinary boilers are composed, is hardly thick enough to 

 retain a stay with security by merely tapping the plate, whereas, if the stay 

 be rivetted,thc head of the rivet %vill in all probahility be soon burnt away. 

 The best practice appears to be to run tbe stays used for the water spaces in 

 this situation, in a line somewhat beneath the level of the bars, so that they 

 may be shielded as much as possible from the fire, while those which are re- 

 quired above the level of tbe bars should be kept as nearly as possible towards 

 the crown of tbe furnace, >o as to be removed from the immediate contact of 

 the fire; screw bolts with a fine thread tapped into the plate, and with a thin 

 head upon the one side, and a thin nut made of a piece of boiler plate on 

 the other, appear to be the best description of stay that has yet been con- 

 trived. The stays between the sides of the boiler shell or the bottom of the 

 boiler and the top, present little difficulty in their application, and the chief 

 thing that is to be attended to is to take care that there be plenty of them ; 

 but we may here reniaik that we think it an indispensable thing when there 

 is any high pressure of steam to be employed, that the furnace crown be 

 stayed to tbe top of the boiler. This is done in tbe boilers of the Tagus and 

 Infernal, constructed by Messrs. Miller. Ravenhill, and Co., and we know of 

 no better specimen of staying than is aflTorded by those boilers. 



****** 



Priming arises from insufficient steam room, an inadequate area of water 

 level, or the use of dirty water in tbe boiler : the last of these instigations 

 may be remedied by the use of collecting vessels, but the other defects arc 

 only to be corrected either by a suitable enlargement of the boiler, or by in- 

 creasing the pressure and working more expansively. Closing the throttle- 

 valves of an engine partially will generally diminish the amount of priming, 

 and opening the safety-valve suddenly will generally set it astir. \ steam 

 vessel coming from salt into fresh water is much more liable to prime than if 

 she bad remained in salt water, or never ventured out of fresh. This is to he 

 accounted for by the higher heat at which salt water boils, so that casting 

 fresh water among it is in some measure like casting water among molten 

 metal, and the priming is in this case the elfect of the rapid production of 

 steam. 



One of the best palliatives of priming appears to be tbe interposition of a 

 perforated plate between the steam space and the water. The water appears 

 to be broken up by dashing against a plate of this description, and tbe steam 

 is liberated from its embrace. In cases in which an addition is made to a 

 boiler or steam chest, it will be the best way not to cut out a large hole in 

 tbe boiler shell for establisliing a communication with the new chamber, but 

 to bore a nund)er of small holes for this purpose, so as to form a kind of 

 sieve, through which a rush of water cannot ascend. 



Part VII. concludes with an enquiry into the area of steam passages, 

 wliich is one of the utmost importance, and as it is not concluded we 

 shall defer any examination of the formulas until another opporfunitv. 



We must observe in conclusion that with each number there is given 

 an engraving of a steam engine, which does not refer to the letter- 

 press, but they promise that wlien tbe subject of the engine is brought 

 forward it will be more fully and properly illustrated than the boiler 

 has been. 



Iron Tubing.— M. Hector Lcdru laid before the meeting of the Paris Aca- 

 demy of Sciences some specimens of cold-drann irou and oilier lubiiii;. A lew years apo 

 the only tublnp made In France, for pas niid otllef purposes, except lead tubing, was iiiuiii* 

 by hnnd. In l':ngl:ind iron drawn lubinK (I'y heat), without soldering, w-as first luade, aiid 

 was imiiorled, liy special pcriuissioTi, Into France, ou account of its vast superiority 'over 

 band.made soldered tuties. Within the lust two years the French have, in this branch of 

 mannfacturc, eclipsed the Kngliih, for they now, by pressure, draw tubing cold, and it is 

 la every resptct perfect— indeed, much more perfect tUau tbe bot-dranu tubing. 



NF,\\- PROJECTED RAILWAYS. 



We give below the decisions of the Board of Trade witli regarH to 

 railways, which we have arranged on a more convenient plan. We 

 regret exceedingly that want of space deprives us of the opportunity 

 of exposing the gross errors and H.igitious transactions of the Railway 

 Department. We have repeatedly deprecated tliese interferences 

 with private enterjirise, for we are convinced that the results will 

 prove of most serious injury to the community and to the engineering 

 profession — as it is, the railway engineers are idready at the mercy of 

 tlie government olTitials. The decisions show a want of sound prin- 

 ciples wliic!i justifies our previous doubts, and makes us very mis- 

 trustful as to the propriety of allowing powers so exorbitant to remain 

 in such hands. The partiality exhibited towards the old companies, 

 the disregard of public interests, and the inattention shown to the 

 most meritorious plans, are features which eminently characterize tlie 

 proceedings of the Board. The rejection of the Salisbury, Exeter and 

 F.dmouth line is a prominent instance of mil-administration, and has 

 no grounds on which it can be justified. Here is a railway proposed 

 to pass along the existing mail route, protecting a vain, ible line of 

 tratiic, communicating with important towns, and having for its ter- 

 minus the packet port of P'aliuouth, and the large and wealthv mining 

 districts of Cornwall. The saving in the journey to Falmouth would 

 be 46 miles, one hour and a half, and 10s., and yet all tliese facts are 

 overlooked, and because there is a line of railway from London to 

 Bristol and another from Bristol to Exeter the public interests are to 

 be totally disregarded. Many cases of great ilagrancy might be ad- 

 duced, but the rejection of the Salisbury and Falmouth line furnishes 

 a case which out-IIerods Herod in the way of government meddling 

 and niismaiiagemeut. We question even whether the Continent could 

 produce any |>arallel to this proceeding, which is equally mischievous 

 and unjustifiable. 



We would seriously urge upon engineers the position in which they 

 now stand and the (irospects before them. The railway engineers are 

 in a state of thraldom, the mining engineers are threatened, and the 

 marine engineers have reason to apprehend a new attack. Three or 

 four years ago it would have passed belief that such things should be 

 meditated, it is even now almost incredible that they have been car- 

 ried into eftisct. It is painful to reflect that our most eminent engi- 

 neers, men who have given the profession an universal reputation, 

 should now be dependent for employment on the hat of a military en- 

 gineer, necessarily incompetent, and that their plans, estimates and 

 designs are to be subjected to the judgment of such an individual. 

 At present the chain is but light, yet the Stephensons, Brunei, Locke, 

 Cubitt, Braithwaite, Rastrick, Macneil, and Vignoles, are as efTec- 

 tually exposed to dictation of the Board of Trade, and as completely 

 at its mercy as it is well possible to conceive. The chain may be 

 drawn tighter, the Board of Trade may become more exacting anj 

 more meddling, but our engineers have bad the bit put in their mout 

 and it is with the Board of Trade to pull the reins. The ultima"', 

 designs of the Board of Trade are, on their own confession, to buy ute 

 all the railways in the country and possess themselves of them, and p 

 then follows that the engineers will become the members of an Englisit 

 Corps dds Ponts et Chausst>e!, a result which no well-thinking mah 

 will desire to see produced, for it must both morally and pecuniariln 

 injure the profession, and through them the public. We expect ally 

 therefore, as engineers and as shareholders, to make the firmest stanu^ 

 in behalf of the rejected lines and against the Eo-ird of Trade. Ther 

 must be no tampering, no paltering, no hesitation, no dependencee 

 no reliance upon anything, but the certain effects of a strong pressure, 

 from without. 



Districts — Counties of Cornwall and Dvvoit. 

 In favour of the— Against the — 



Cornwall * Railway (Plymouth to Fal- Cornwall and Devon Central Hallway, 



mouth), Great Western and Cornwall Junction 



West Cornwall Railway (up to the June- It.iilway ; 



tioD with the Cornwall Itailvvay), 

 Saint Ives Junction Railway j 



And recommendin<f the postponement nntii a future period oj the — 

 North Devon (Crediton and Barnstaple) Railway, 

 Kxeter and Crediton Itailway, 

 Torquay aud Newton Abbot Itailway, 



Districts of Berkshire, Hampshire, Jf'iltshirc, Dorsetshire, Somersetshire, and 



Devon, tying intermediate between the Great Western, Bristol, and Exeter, and 

 London and South H'cstern iiuihvaijs. 



In favour of the— .lu'aiust tlie— 



Reading, Basiugstoico, and Hungerford Basingstoke and Didcot Junction Railway 



Railway (Great Western), (London and South Western), 



Wilts and Somerset Railway— subject to London and South Western— Salisbury 



the condition of applying to Parlia- to Yeovil, 



ment in a future session for an iin- London and South Western— Hook Pit 



proved line of communication towards Deviation, 



Bath and liri-toi, Salisbury, Dorchester, and Weymouth 



Bristol and Kxeter— Durstonand VeOTlL Railway, 



Branch, 

 SouthamptoQ and Dorchester Railway ; 



