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CORNWALL POLYTECHNIC SOCIETY.

The preceding extract is introductory

"Table 1. to a set of tables, by Mr. Enys, “ relative “ The volumes of steam from one of water to the properties and practical application are from the tables by Clément Desormes. of steam, which are of such general in- The efficiency is added, expressed in lbs. one terest, and calculated to be of such ex. foot high, or the force and space of the steam tensive utility, that we need make no

produced by the evaporation of a cubic foot of

water. apology for transferring them, along with

" Table 2. some further preliminary remarks, to our

“ Shews the common theory of the advanpages.

tage of using steam expansively in a different “ The simplest form of calculating the form. The pressure of the steam is taken moving power of steam, is the extension to all higher at each expansion, so as to produce pressures of the mode employed by Tredgold an equal mean pressure in the cylinder, the for the power of 'steam of atmospheric pres- steam being cut of at a fractional part of the sure. The term efficiency used in these tables, cylinder to produce the required expansion ; was suggested in a paper published in the instead of the impracticable scheme of inTransactions of the Royal Society, in 1827, creasing the length of the cylinder at each by Mr. Davies Gilbert: this word prevents expansion : this table assumes that pressure confusion with engineer's power, or horse is inversely as the expansion, though not power, which is available efficiency, or the quite correct. neat power of the engine applicable to the

Table 3. owner's use. It is equivalent to “ The power “ The first column gives the steam presof steam to produce motion” of Tredgold; sure due to the theory to produce a mean The power exerted by steamof Wood on pressure of 16 lbs. per square inch in the cyRailways ; " Mechanical power of steam.' linder. The table is calculated from the A similar distinction is also required between second column, in which the steam pressure the gross work, including inertia, friction, is taken higher as a rough correction of the &c., and the neat work done. Effect may be error of the assumption, when the temperaapplied to the former; Duty to the latter. ture is diminished.”

TABLE, No. 1.

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1.25 1.5 1.75 2. 2 25 2.5 275 3. 3.25 3.5 3.75 4

1.8437 3.6875 7.375 11.0625 14.75 18.4375 22.125 25.8125 29.5 33.1875 36.875 40.5625 44.25 47.9375 51.625 55 125 59•

11801
6198
3229
2217
1700
1384
1171
1016
899
808
733
672
620
676
539
506
477

37 70 135 197 257 316 372 430 486 541 596 651 705 759 809 864 917

124.6 150.8 179.6 197.6 212: 223.8 232.3 242:7 250.7 257.9 263.9 269.8 275 279.8 284.6 288.8 292.9

2653 531 1052 1593 2124 2655 3186 3717 4248 4779 5310 5861 6372 6903 7434 7965 8496

3133165 3291138 3329198 3531681 3610890 3674520 3730806 3776472 3818952 3861432 3892230 3938592 3950640 3976120 4006926 4030290 4052592

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Illustrative of the advantage of working High Steam expansively, as practised in Cornwall.

TABLE 3.

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case.

“ The foregoing tables appear to show that strokes made by the piston, and not high steam is advantageous, independently necessarily the space through which it of expansion; but it must be recollected, that in this production, the air and smoke must

passes ; and secondly, it derives its mo

tion from the bob through a lever, so that be allowed to escape from the flues, at a

it measures the arc uf a circle instead of higher temperature, which will tend in some degree to counteract any advantage derived

the tangent to it; in other words, it show's from its use. My opinion is favourable to

the distance passed over by the end of the as low steam as will give the full benefit of

working beam instead of that travelled the expansion applicable to each particular by the piston. Something much better

is therefore still wanted. We are glad to observe, that among Another of the steam-engine desithe premiums offered through the medium derata of last year was an exact method of the Society for the current year, (and of "measuring, and registering the very liberally 6 not confined to the

exact quantity of water supplied to the county,)”, there are two by Mr. H. H. boiler.” This is now considered to be Price, C.E., “ for the best, and second fully supplied by the water-meter of best practical plans for adapting to steam- Captain T. Richards, of Wheel Vor, vessels" that method of working steam of which a drawing and description are expansively, the advantage of which, is given in the present Report. The prinso strikingly demonstrated by the pre- ciple on which this meter is constructed is ceding tables. It is accompanied, how- that a vertical measuring pole, and the ever, by this very proper caution, that parts connected with it, shall be thrown “due régard must be had to the essential out of action whenever the feed is turned difference between a single-acting engine off, but driven down and forced up by the working pumps by a lever, and two water whenever it is passing into the double-acting engines working with a boiler, and that this shall not take place crank."

without acting on a counter, and registerThe premium offered last year by the ing the quantity delivered by showing the Society, for the best method of measuring number of inches the pole has gone uver the length of the struke of the piston, in its down stroke. Mr. Richards prohas been awarded to a counter invented

poses that the measuring pole should be by Mr. M. Loain, which is about to be of such diameter that the cubic content of introduced in the United Consols mines.

every inch in length should be equal to a This apparatus is admitted, however, to quart of water, in which case the indicahave two serious defects; in the first tions of the counter would be in quarts. place, it registers only the number of In this plan there are no additional valves

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LONDON GRAND JUNCTION RAILWAY.

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or cocks, and the only part requiring the terrestrial magnetism in different parts adjustment is a stuffing-box for the mea- of England, Ireland, and Wales,” as suring pule.

ascertained by this deflector; and no A premium which was offered last year tices of several inventions favourably by J. Buller, Esq., for the best essay on thought of by the Society, though not the natural history of the pilchard, has comprehended within the scope of its produced an exceedingly interesting paper premiums, such as Hoskin's Portable on the subject by Mr. Jonathan Couch, Punching Press (the engraving and de. from which, however, we can only afford scription of which we gave in our last room for one brief extract:

number), Wilton's Miners' Theodolite, • " The quantity of pilchards caught on the Loqm's Wheel Wrench, &c. coast of Cornwall, can scarcely be made the We are pleased to find it reported that subject of calculation, since no account is the funds of the Society are, as they detaken of what is reserved for home consụmp- serve to be," in a fourishing condition." tion; we therefore can only here remark on

" Their means have exceeded their dis. what has been recorded to have been exported. bursements." The largest schuls are found late in the season,

Happy would it be for

nations, as well as individuals, were they and commonly in sheltered situations, at a time when the weather is troubled, A few

to keep always within the same prudent

limits. Of the evil consequences of ex, years since, a capture was made in Hemmick Bay, to the amount of two thousand two ceeding them, a memorable illustration hundred hogsheads; and Borlase reports the

is furnished by an item in this antaking of three thousand hogsheads at one nual budget of our Cornish friends, shooting of the sean : but even this is not the which still remains to be noticed. The greatest on record ; for, in November, 1834, item to which we allude is a “Chronologiit is said that three thousand five hundred cal Map of the Wars of the British Em. hogsheads were landed from one sean at St.

pire from the revolution in 1688-9 to Iyes; and on another occasion, ten thousand

1835," showing how, from small begin. hogsheads were enclosed in that port in one

ningss-from a inathematical line without day, though not in one sean; thus producing the enormous multitude of thirty millions

depth or breadth our national debt in, of living creatures drawn at once from the

creased (though the wars aforesaid, and

all the destruction of life and property of ocean, for human sustenance.

which wars are the invariable cause) to “ The greatest number I was ever witness

a seam of 860 millions thick!!! to, as taken in a drift-boat, was 40,000, but I have been informed, on credible testimony, of 80,000 taken at once, in a single capture; and it was supposed that this alleged number LONDON GRAND JUNCTION RAILWAY. fell short of the whole. About the middle of

(From Report of the House of Commons Committee, the eighteenth century, it was not uncommon

on the Bill for this Railway.) for the drift-boats to get so much fish entangled in their nets, that they were obliged

By an Act passed in the third year of to sacrifice a portion, by giving some of their

his present Majesty's reign, a Company nets and all their contents, to those who was empowered to make a railway from would take care of them, on condition that Birminghain to London, terminating on the pets were returned to them again within the north side of the Regent's Canal, a few days:-the condition was, assistance in Camden Town. In the last session, an securing the remainder.

Act was passed for making a branch Besides the articles we have thus par- from that point to Euston-grove, in tjcularly poticed, there is an Essay “on the parish of St. Pancras, for the conthe various Diseases incidental to Miners, veyance of passengers and light parcels their Causes, &c.,” hy C. Carlyon, M.D., only, but not of merchandise and goods. which as a first but able contribution to There are at present, therefore, no meang. an important brauch of medical statistics for the conveyance of the present num, too much neglected, deserves, and we ber of passengers proceeding from Camhope will altract, the attention of the den Town to the City, or for those who. author's professional brethren ; a descrip- will be brought by the Birmingham tion of some improvements made since Railway, except the ordinary vehicles last year by Mr. R. W. Fox on his dipp- plying in the streets. The only present ing needle deflector, (see Mechanics' Ma- means for the conveyance of goods from gazine, vol. xxiii, p. 97,) and a chart and Camden Town is the canal, but as that table showing the dip and intensity of is at no point nearer the City than the

THE PNEUMATIC RAILWAY.

New-road, it could not be available for liam Barnes, Esq., surveyors, in the that purpose. Evidence was adduced to city of London, as to the valuation of show that it would be a great advantage the property to be purchased. Your to trade and commerce to have a railway Cominiitee, therefore, see no reason to cominunication for goods and passengers apprehend it will be insufficient. ex'ended to the City.

The estimated annual charge for the The amount of income expected to railrvad, when completed, including all arise from the conveyance of passengers incidental expenses, is 40,0001., which and goods is 113,5591., of which 90,8181. was founded on the charges of similar is expected from the conveyance of pas- works now completed. sengers, and 22,7411. from the convey- The evidence fully satisfied your Comance of goods which are the manufac- mittee that the return would be sufficient tured articles of Biriningham, Manches- to support all the annual charges and ter, and other manufacturing towns, and maintenance of the railroad, and leave live and dead cattle to Smithfield, New- an adequate profit for the shareholders. gate, and Farringdon markets.

Your Committee think it desirable The proposed railway is the extension the House should be informed that, and completion of the Birmingham Rail- as this railroad follows the course of the way, and is an integral line between its River Fleet, a considerable portion of respective termini.

the ground is not built upon; so that, The only line which can be considered in fact, the arches under the railway will as a competing one is an inclined plane, form as many dwellings as the railway now in progress, from the Birminghain will displace. Railway at Camden Town to Euston

A great part of the houses that will grove, a distance of nearly a mile ; but be taken down in and about Hattonthat is only enabled to convey passengers garden and Saffron-hill are in a dilapiand light parcels. The proposed rail- dated and dangerous condition. Several way has the advantage of conveying pas- parochial officers gave evidence as to the sengers to the centre of the metropolis, state of the neighbourhood, and the adabout three times that distance, yet at vantage it would be to have an opening one-fourth less charge. It is also to be made through that confined and unadapted for the conveyance of goods, healıhy part of London. which would otherwise have to be carted from Camden Town.

The whole line will be worked by locomotive engines, without any assistant Sir,- The peculiar formation of the air or stationary power.

tubes which, in one way or other, are inThere seems to be no peculiar en- tended to form the carriage way of the gineering difficulties in the proposed projected pneumatic railway, appears to line.

be that to which the attention of the pubThere are no tunnels.

lic has been especially directed in the vaThe steepest gradient is 1 in 273, or rious articles which have appeared in the 19 feet in a inile. The smallest radius Mechanics' Magazine on this subject ; of a curve is half a mile.

but I am not aware that anything bearing The length of the line of railroad is expressly on the mode of procuring the two miles and fifty chains. There are current of air in the tubes has been puhno branches.

lished. It seems intended that steam, The plan seems, in an engineering applied through the instrumentality of point of view, well fitted for the objects stationary engines, should be the geneintended.

rator of power, and that this power should No turnpike road will be crossed by be employed to extract the air of the the proposed railway on a level.

tubes through the agency of air-pumps. The estimated cost of the whole work, Have not some objections been made to including the cost of property, is 600,0001. this agency, raised upon the reciproThis estimate was proved by George cating action of the pumps, and the elasRennie, Esq., and supported by the evi- tic nature of the element to be operated dence of Colonel Landınann, the en- upon ? If these objections have been gineer of the Greenwich Railway, as thought formidable, might they not both respects the engineering departnent; be overcome by the simple application and by George Smith, Esq., and Wil- of fans instead of pumps, which are now

THE PNEUMATIC RAILWAY.

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