64 



THE Cn^IL ENGINEER AND ARCHITECTS JOURNAL. 



[February, 



cut oft' tlie stp«m at one-tiftli of the stroke, these engines consume 

 2ilbs. ]ier luiur foi' liorse-pouer ; 12 hours per day, 312 flays, it will 

 give per annum about GU2 tons at .)S. per ton, or i£150 Ms. 



The ropes will not require renewing ofteuer than once in twelve 

 months because there are not jerks or stoppages at the stations, the 

 cost of this, after deducting the value of the old, will be £525. The 

 four engines, engine-houses, and machinery, would cost £'8,000, at 

 fij per cent, would be £520. The annual repairs to boilers, engines, 

 and machinery, taken as by Messrs. Walker and Rastric, including 

 hemp, oil, and tallow, at 14.s'. Sd. per horse power, will be £ loij ys. 

 The interest, wear and tear of pulleys would be ,£300, oil to ))ulleys, 

 and men to grease them, £144, all which sums amount to £1,745 ISs. 



The whole yearly expense of the stationary system amounts to 

 £1,745 Is.v. The expence of the locomotive system, £4,540, making 

 a difterence in favour of the stationary of £2,S00 2s., which sum, 

 added to the £2,000 per annum saved in the first cost of the railway, 

 amounts to £1,800 2s. If the saving of £4,800 per annum does not 

 speak to the ])ockets of the shareholders, nothing I can say will do it. 

 If gentlemen of fortune wish to have railways, let them have locomo- 

 tive engines upon them by all means to show to their wives and 

 daughters, but if men of sense and men of business wisli to have their 

 shilling's worth for a shilling, let them search and see if these things 

 are so. 



Diogenes. 

 Sheffield. 



( To he concluded.) 



ENCROACHMENTS AND RECESSIONS OF THE SEA. 



It appears that the tendency of "/7/e sea to pnserre its paralltl," has 

 been pointed out in No. 27 of the Journal as the origin of the encroach- 

 ment and recession of the sea, and that the action of the influx of 

 water is increased in bays in proportion as the projecting point to the 

 westward is greater, while it is assumed that the filling up of bays 

 and cutting of headlands are equal. The meeting of the tides from 

 the Northern and Southern Channels to the eastward of Hastings, 

 renders a reference to the geological facts to the westward most ad- 

 visable. 



The beds of sand, sandy rock, and clay, denominated the Wealden 

 formation, are supposed to dip from Hastings to Beachy Head, and to 

 disappear under the chalk at that point. Tlie outcrop of the highest 

 sand-rock bed is visible from thence to the Sea Houses, East Bourn, 

 but in the interior, the height of the beds above the sea level seems 

 in some proportion to their hardness. Pevensey Castle is placed 

 towards the end of one of these low ridges, so formed, and Pevensey 

 Level consists, judging from the drains, of the outcrop of the clay 

 beds, and not of the detritus of the chalk clitfs to the westward. 

 Romney Marsh is sometimes considered as a more modern deposit of 

 silt; its position, in some geological maps, is in front of that part of 

 the Hastings sand, dipping easterly from the anticlinal line near Has- 

 tings; it is said to have successive ranges of beach banks, of a form 

 nearly corresponding with the present coast line. If these opinions 

 are correct, it differs essentially in its formation from Pevensey levels, 

 where, 1 believe, a small extent only of beach, covered with grass, 

 exists at the eastern end. The accumulation of beach at Langney 

 point, perhaps amounting to 1000 acres, is at a lower level, and is 

 almost as bare of grass as the shore on which the sea now beats, while 

 its character is similar in all points to the mass of beach at Dunge- 

 ness. 



It has been most distinctly proved, that an ancient raised beach 

 exists around the coast of Cornwall and Devon elevated in diflferent 

 sites from 5 to 30 feet or more, and covered with a Grauwacke de- 

 tritus termed alluvial by Dr. Buckland. 



At Brighton there seems an equally distinct trace of an equivalent 

 raised beach covered by a diluvial chalk detritus, as due to a similar 

 cause in different sites. Perhaps the grass-covered beach banks of 

 Romney Marsh and Pevensey Level, are due to the same geological 

 epoch, and the accunuilations of beach at Langney point and Dungeness 

 belong to the present era. 



Previous to the admission of any arguments derived from the beach 

 at Hastings Bridge, it must be proved to be a portion of the present 

 sea beach, as its site and height above the sea would suggest the idea 

 of its forming a part of a raised beach of a former geological period. 



In reference to the question of equal cutting and filling, it has been 

 shown by geologists, that the waves are the cutting agents of the sea 

 in the destruction of clitts, and that the tides or currents sweep the 

 finer particles into deeper water, and leave the harder part on the 

 shore, which are rounded into beach ; the whole coast, wliether liigh 



or low, is] fringed with a variable quantity of beach, which is driven 

 along the coast in proportion to the diagonal blow of the waves, and 

 consequently tlie mass is in motion eastward, as due to the mean 

 excess of the westerly over the easterly waves. 



The effect of groins is easily seen ; the beach is collected on the 

 weather side, while the lee side becomes bare ; hence equal waves 

 have a greater cutting eft'ect on the softer materials of the exposed 

 shore or clill', and less on the side protected by the accumulation of 

 beach, and in their construction, the principle to be regarded is the 

 retardation of the exact quantity of beach requisite for the protection 

 of each spot, allowing its regular passage either way ; the groin 

 referred to at Hastings is probably either too large, or too high at the 

 outer end — the result is inevitable, the shore on each side will be 

 overprotectcd, or overbared, alternately, according to the direction of 

 the wind. 



My object has been rather to question the data assumed than to 

 attempt to elucidate this subject by a reference to the numerous ele- 

 ments essential for that purpose, partly with a hope of inducing civil 

 engineers, to measure and recoril clearly the geological facts which 

 may happen to come under their notice in the course of their pro- 

 fessional labours. 



ON THE COMPARATIVE POWER OF STEAM ENGINES. 



Siu — Though I have read with great pleasure tlie communication of 

 Mr. Armstrong on the comparative effects of the Cornish and Lanca- 

 shire system of working steam engines, yet I must object to the ac- 

 curacy of the estimate of the gross horse power of the East London 

 Water-works engine, and I trust the following observations will induce 

 others to take into consideration the propriety of confining the terra 

 Duty to the distinct and definite meaning in which it has been 

 employed in a large mining district for a longer period, than the 

 existence of factory steam engines. His paper is entitled, "On 

 the Comparative Effects," the table is headed "Comparative Duty;" 

 the pounds raised one foot high per minute -^ 33,000 are termed 

 "Gross Horse Power," while this same quantity 194 is termed " Net 

 Effective Power," previous to the deduction oif one-third for the re- 

 sistances of the shafting ; yet each is actually derived from the same 

 elements, viz., the average steam pressure taken by the indicator in 

 the Lancashire engine, and the supposed gross load + an allowance 

 for " friction of the engine itself," in the Cornish engine X in each 

 case by the space in feet per minute for gross horse power. The 

 gross pressure of steam whether observed or calculated, is equally 

 capable of being referred to the variable time of the consumption of a 

 bushel of coal (114 pounds), but then such a word as Efficiency would 

 be useful in distinguishing it from Duty. See Phil. Trans., 1S27. 



Duty as introduced by Watt, and retained iu Cornwall, is founded 

 on different elements, viz. the nett work performed clear of pitwork or 

 shafting resistances, X by the space of motion per bushel of coal, it 

 is always calculated, but if the water was measured or weighed, it 

 might be called active duty: the usual mode of obtaining the load in 

 the shaft is by squaring the pump diameter in inches, X by the lift in 

 fathoms, X by 2-0454 pounds, the weight of a cylinder of water one 

 fathom in length and one inch in diameter : the omission, however, of 

 the two last decimals, only attects the three last figures of the duty in 

 millions. 



Duty and gross power are hence the extremes, while gross power 

 minus engine resistances, and duty plus pitwork or machinery resist- 

 ances become respectively nett power, =: engineer's horse power, and 

 gross work performed, and these on a statical view are equal to each 

 other — the word effect will be found a convenient term to distinguish 

 gross work done from duty, It has always been necessary to ascertain 

 whether the beam leverage is equal, if not so, due allowances must be 

 made for the differences ; it will be .dso convenient to use the word 

 pressure as equivalent to force, and force X space as power, while 

 gross and nett load become respectively effect and duty. 



In the arrangement of the East London Water-works engine, a 

 weight of 29 tons is lifted at the outer end of the beam during the in- 

 door stroke, but not without some packing friction, as well as a column 

 of water on the lower valve of a diameter equal to that of the plunger 

 pole — together, these form the gross load on the in-door or acting 

 stroke. During the out-door stroke the weight returns and lifts the 

 water above the lower valve, overcomes friction, &c. &c. As friction 

 increases in bad pitwork, at least, as fast as the deficient water delivery — 

 while the reverse takes place in good, the calculated duty of pumping 

 engines probably ,bears a closer approximation to the whole work done, 

 or effect, than might be expected. 



