1839.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



467 



finds the following general relation between the different data of the 

 problem, 



«^''+<"+^'){^q^ + '"^^)- 



(A.) 



- al = Ral, 

 ^q / I' -1-c ( -t-c q 



in which P is the pressure of the steam on the piston, before the 

 communication with the boiler is intercepted, and R the mean resist- 

 ance on the piston. This equation is then transformed into another, 

 independent of I-", by supposing the evaporation of the engine, or 

 rather its effective evaporation, to be known. This new equation is, 



S 

 a 



+ l"g' 



l + c] 



(1-) 



n+ql<\l'-\-c ' "'''I'+c 

 where S is the volume of water evaporated per minute, and trans- 

 mitted to the cylinder in the form of steam, / the length of the stroke, 

 /' the length of the portion traversed by the piston at the moineiit the 

 steam is cut oH', r the clear.uice at each end of the cylinder, that is, 

 the length of a pcjrtion of the cylinder whose capacity is equal to that 

 of the waste space beyond that traversed by the piston, wliich is 

 necessarily filled with steam at each stroke. 



In order to make use of this equation, it is evident that we must 

 know, not only the q\iantity of water actually evaporated, but also the 

 quantity lost through the safety valve, or by any other means. 



The quantity U, which is the total resisting pressr.re on the unit of 

 surface of the ])iston, is afterwards decomposed into three parts, 

 namely, the resistance arising from the motion of the load, which the 

 author calls ;• ; that arising from the friction of the engine, which is 

 expressed by Cy+Sc), calling _/' the friction of the engine unloaded, 

 and 5 the augmentation of that friction per unit of the load )■; and the 

 pressure on the opposite side of the piston, which is represented by 

 /', and is cq\ial to the pressure of the atmosphere in high pressure 

 engines, and to the pressure of condensation in condensing engines. 

 Thus, 



R = 0+5) r+p-\-/. 



Substituting this value for R, and the expression /i for 



I' . , l + c 



7+c + '°^-Wc' 

 the equation (1) becomes 



_S k_^_ 



" - a n+q [(l+5)r+;,+/] 



In the calculations relative to locomotive engines, three 

 are to be introduced into the expression of tlie resistance 

 express the resistance of the air against the train, which, increasing 

 as the square of the velocity, could not be neglected without error ; 

 the second to express the resistance offered by the engine itself in the 

 transport of its own weight on the rails ; and the third to take account 

 of the resistance causeil by the blast-pipe. 



The abo\'e general equation appears to be very complete, and, pro- 

 vided we are furnished with the means of ascertaining the quantity of 

 water which actually passes through the engine in the form of steam, 

 as well as the amount of the various parts of the resistance, and pro- 

 vided also the constant values of v and q do not cause too great an 

 error practically, we have no hesitation in saying that it will be found 

 of great utility in proportioning engines and boilers to the w'ork re- 

 quired to be done. 



terms more 

 the first to 



RIVER OUZE OUTFALL IMPROVEMENT. 



This improvement promises to be the prelude to others, and is of 

 great national importance, the success of which will lead to similar 

 improvements in other parts of the coast of England, thereby adding 

 many thousand acres of rich fertile land to the kingdom; in our own 

 judgment we have no doubt of its success, if it be not marred by parish 

 squabbles and the grasping appetite for pecuniary compensation by 

 adjacent landed proprietors. 



We have before us an elaborate' report relative to the above im- 

 provement, by Sir John Rennie, accompanied by plans ; it ouglit (o be 

 read by all lauded proprietors connected with property on the sea coast. 

 We regret that we cannot find space for the whole of the report, how- 

 ever, we will give a lengthened extract of th.e most interesting part 

 of it. 



The plan for ohtaining this most desirable result consists in deepening the 

 Outfalls of the Ou/.c, tlic Nciie, the M'illiani and the Wclland, by con-ecting 

 and straightening their cliimncls, continiiig llicin between salistaiitial and 

 wcU-formed banks, can7iiig all of tliem into deep water, and there uniting 

 the whole in one geueral grand channel in the centre of the Great Wash (as 



shown uiiou the accomiianyiiig plaa) ; a work wliicb, altliougli of coasider- 

 able magnitude, yet presents no dithcultics in the execution which caiuiot he 

 readily overcome by the provision of adequate means. Tlie natural consc- 

 qaence of these measures will he the closing of all the present minor chan- 

 nels and shoal water of the Wash, which are now fed and kc|)t Ojieu cliictly 

 by the rivers above mentioned, tlie circulation of the tide, and tlic agitation 

 produced l>y the wind over such an extensive surface, which prevents the 

 alluvial soil held in suspension by the waters from subsiding, so that it is 

 again carried back to sea. As soon, however, os the present channels are 

 (hvertcd, and other artificial means resorted to to cheek the currents and 

 waves, and assist the accmuulatinn of warp, then the whole of this extensive 

 space will become still water, and the silt and warp which is held in suspen- 

 sion, amounting to a large proportion, will he <le]iosited, and thus in a com- 

 paratively few years will raise the suh-suil sufficiently high, when it will be 

 converted into good land, and may lie wholly ciubauked from the tide. By 

 pursuing the above system of operations regularly and judiciously, the soil 

 will accuiiiulate according as the subjacent space is removed from the action 

 of tlie waves and currents, and thus the acquisition of land will be progres- 

 sive, and contribute to the ex|iense of acquiring the remainder, until the 

 whole quantity be completed; indeed about 90,000 acres are now hare at 

 low water, and a large portion of this, viz., about 10,000 acres, are fit to be 

 taken in. By way of illustration, it is only necessary to observe, that a por- 

 tion of the old channel of theOuzc, cniitaini'ig 800 acres, which was deserted 

 by the Eau Brinlv Cut, has been warped up, by the course of nature alone, 

 25 feet, in five or six years, and the whole 800 acres is now under cultivation 

 ami worth from 30?. to 70/. an acre; 1,300 acres were embanked from the 

 Nene Wash eight years since, and let for nearly 2/. per acre ; since that period 

 the warjiing of the remainder, containing between 4,000 and 5,000 acres, has 

 been very rapid, amounting to in parts 14 feet perpendicular, hy the mere 

 operat'oas of nature alone; this has been further increased hy the addition of 

 some slight works within the last two months, a'ld the whole of this will be 

 ready to be taken in in about two years from t!ie present time, and will be 

 mucii more valnahlo than the 1,300 acres above mentioned ; and if the system 

 now a-lopteil of assisting the accumulation of soil had been commenced earlier, 

 1 have no doubt hut that the whole of the NeneVvash might have been under 

 cultivation by this time ; above 3,000 acres, I understand, have been taken 

 in also along the shores of the Welland and Witham, and the northern side 

 of the Great Wash. These it should be observed arc mere detached, isolated 

 operations carried into eifect without any general plan and system, ami are 

 necessarily neither so efficient or economical as when carried on upon a great 

 uniform and well-cnmbined scale ; still, however, they have been veiT pa-o- 

 fitable, and have well repaid those who undertook tlicin. The Outfall of the 

 Ouze is the first and principal oiieration, and !)y correcting its course and 

 channel three miles may be saved ; and an additional fall of nearly 6 feet 

 may be gained in the low-water fine between Lyiin and the Thief Beacon, 12 

 miles below the town. There are three lines by whicli the new channel may 

 he carried; first, by taking it through the inclosed lands belonging to the late 

 Lord William Beatinek ; secondly, by straightening and confining it liy jetties 

 rather more seaward than Xo. I into- deep water; and, thirdly, hy carrying it 

 through the Peter Black Sand hy jetties along tlie Norfolk siiore into deep 

 water' in tliat direction. The first Plan is, upon tlic whole, sh.orter hy one 

 mile than the Plan, No. 2, and by the first Plan an additional fall of one foot 

 would be gained in the current ; it would also be more certain of execution, 

 more easily maintained w hen completed, and sooner accomplished, although 

 rather more expensive in the outset. 



The Plan, No. 2, would be rather longer, more uncertain, and not so good 

 when completed. 



The Plan, No. 3, is objectionable, in consequence of the great length of 

 shoal water, viz. 11 miles, through which the uork would liavc to be carried 

 before it w-ould arrive at deej) water ; and there would be a greater difficulty 

 in preserving it when made, in consequonce of the extensive tract of shifting 

 sai.ds which accumulate along the shore. 



The expense of Plan, No. 1, would amount to the sum of 250,000/., and 

 the other two rather less. 



The Outfall of the river Nene being 5 feet 8 inches lower than that of the 

 Oiizc, with the exception of being advanced, is now in such a perfect state, 

 that much more fall cannot be expected ; by prolonging it downwards, how- 

 ever, into deep water, so as to unite with the Ouze, the whole of the inter- 

 vening space of Land, amounting to several thousand acres, would be gained 

 ill a short time. 



The Welland and Witham Outfalls, particularly the former, arc now in a 

 verv defective state; they may however be comiileted either hy carrying them 

 direct across the Clays uito Clayliole, or by the Maccaroni or South Channel, 

 to join the Nene and the Ouze. The advantage of the former plan is, that 

 the dist.inee to deep water is considerably shorter, .and, in consequence, it 

 would be sooner elfcctcd; and custom has hitherto jioiuted out Boston Dcepa 

 as tl;c natural entrance or roadstead both fur the Welland and the Witham. 

 On the other hand, looking forward to one general grand plan, and the pros- 

 ]icct of maintaining the general OutfaU open, there can be little doubt hut 

 that the greater the body or mass of fresh and tidal waters that can be brought 

 into one channel the better, and the greater the certainty of its being .able to 

 maintain itself open. 



In order to ctiVct this cnl.argcd \icw of the subject, the junction of the 

 William, the AVcdhmd. the Ncnc and the Ou/.e into one common Cutfall in 

 the centre of the Great \\'asli, appears the best and most certain plan : more- 

 over, presuming that the >Yitljam and the Welland be carried separately into 



