122 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



I Apbil, 



5. That the iron columns, beams, and t)rick arches he of a strenctli suffi- 

 cient not only to support a continuous dead prt-s&uie, but aUo to resist the 

 force of impact to which they are subject. 



Lastly. That in order to prevent the columns from being melted, a current 

 of coldair be introduced into the hollow of the columns from an arched 

 tunnel under the floors. 



Mr. Uraidwood argued that there could be no doubt, if the second princi- 

 ple could be enforced, a fire would go out of itself; but it was very doubtful 

 if the object was not defeated hy carelessness in leaving a door or window 

 open just at the time when a fire occurred. The fifth principle showed that 

 Mr. Fairbairn had not laid sufficient stress on the loss of strength to the iron 

 consequent on an increase of temperature j and the last principle, it was 

 thought, would not be likely to answer the purpose, as a specimen of IJ 

 inch cast-iron pipe, on being heated in the centre, with both ends open, and 

 a current of air passing through it, gave w-ay, on one end being held in a 

 vice and the other pulled with slight force by the hand, after an exposure of 

 only four minutes in the fire. 



For these reasons and others, the author submitted that large buildings, 

 containing considcraMe quantities of combustible goods, and constructed on 

 the usual system, v\ere not practically fire-proof; and that the only con- 

 struclion which would render such buildings safe, would be groined brick 

 arches, supported by pillars of the same material laid in cement. The author 

 was also of opinion, that the loss by fire would be much reduced if ware- 

 houses were built of a more moderate size, and completely separated from 

 each other by strong party-walls, instead of being constructed in immense 

 ranges, into which, when fire once penetrated, it set at defiance all efiforts to 

 extinguish it. 



In the discussion which ensued, the accuracy of Mr. Braidwood's general 

 statements was fully accorded ; and it was generally acknowledged, that the 

 principles upon which many buildings, particularly dwellings, were con- 

 structed, were very erroneous. It was argued, that even with the ordinary 

 materials, if attention was paid to filling in the partitions and ceilings, as 

 practised in France, and mentioned in Professor Hosking's book on the con- 

 struction of buildings, using slate or stone for the stairs, as from its present 

 cheapness might be done, taking care to support the steps properly, a fire 

 would spread very slouly, and would allow ample time for the escape of the 

 inhabitants. Beardmore's, Fox and Barrett's, and Nasmyth's new systems 

 of flooring, were all alluded to ; as was Mr. P. Fairbairn's fire-proof dwelling, 

 house at Leeds. Chuhb's, Marr's, and other fire-proof safes were advan- 

 tageously mentioned, and were shown to have eftectually preserved the 

 deeds within them in the most intense conflagrations. 



March 13. — The paper read was "A description of the Camden Station 

 of the London and North- H'estcm Railway." By Mr. R. B. Dockrav, 

 M. Inst. C.E. 



In the first design of the railway, in 1833, this station was intended for 

 the sole terminus of the line, and, after much discussion, thirty acres of 

 ground were purchased, although that quantity was considered pre|iosterousty 

 large. A very short time demonstrated the necessity for the establishment 

 of the Euston Station solely for passengers; and fourteen acres were there 

 secured, and ultimately covered with buildings. The whole station at 

 Camden was then devoted to goods and cattle ; and, although in the original 

 design great care was taken to anticipate the wants of the traffic, yet such 

 has been the rapid development of the railway system, that in the space of 

 ten years it has proved necessary to sweep away almost every vestige of the 

 original constructions, and entirely to remodel the station. These changes 

 have been partly produced by the increase in the goods' traffic, which was 

 first undertaken by the great carriers, who built large warehouses on the 

 company's land. The whole system has, however, been reformed, and the 

 company do all that business, and are responsible to the public for the due 

 performance. 



As the increase of the traffic progressed, the trains in the sidings fre- 

 quently became of such length as to cause danger to the passenger trains ; 

 it, therefore, became necessary to alter the whole disposition; which has 

 been so done, as now to give a length of double line of 2,500 feet, for the 

 goods' wagons only, entirely clear of the main line. 



Another reason for the alterations was the demand by the public for a 

 more rapid rate of tr.avclling : this demanded heavier and larger engines, 

 and neccsiitated wider buildings and larger turn-tables ; in fact, everything 

 required to be remodelled ; — and the results of all these changes were 

 shown in detail in the paper and the illustrating drawings. 



The circular engine-house, 100 feet diameter, to contain twenty-four 

 engines and tender, with a central turn-table, 41 feet in diameter, and an 

 iron roof, was excellently described ; as were also the other engine-houses, 

 stores, warehouses, sheds, &c., with their appurtenances; and among the 

 external works, the new wrought-iron bridge, at Chalk-farm, on Mr. K. 

 Stephenson's box-girder principle, and the wooden lattice-bridge over the 

 Regent's canal. 



The supply of water for the locomotive engines was then treated of at 

 some length, and exhibited some curious anomalies. The only water that 

 could originally he used was taken from wells at Tring and at Watford ; an 

 attempt was, however, made to obtain a supjjly at Camden Station, first 

 from the Regent's canal, and then by sinking a well down 145 feet into the 

 chalk, or to a total depth of 300 feet below Trinity high-water mark. The 

 water from the sand stratum was excluiled, and aiihuugh onlv that from the 

 chalk was pumped up, which ought to have xjossessed the same qualities as 



the water at Tring and \A'atford, derived also from the chalk, yet it was 

 found to cause the locomotive to " prime," or flush water through the 

 cylinders, with the steam, to such an extent as to seriously impede the pro- 

 gress of the trains. This was shown, by analysis, to arise from the excess 

 of carbonate of soda contained in this well water, which there was an entire 

 absence of in the waters of the wells at Tring and at Watford. 



The well, therefore, became useless for the engines, but the water was so 

 excellent for household and other purposes, that it has been employed for 

 the general uses of the Station, and for the hotels and houses belonging to 

 the company. 



Some idea of the extent of the Station was given by the statement, that 

 the length of single line of railway, exclusive of the main lines, exceeded 

 twelve miles. There were 112 sets of points, 196 turn-plates, and 110 cranes, 

 varying in power from l\ tons to 20 tons. The area of goods' sheds was 

 upwards of 135,000 superficial feet, and that of the platforms was 30,000 

 feet. 



The annual consumption of gas exceeded 6,000,000 cubic feet. 



The discussion that ensued turned chiefly on the causes of the excess of 

 alkalinity in the water at that spot, and it was suggested that it might be 

 owing to the rapid filtration of surface water through a crevice in the chalk 

 upon which that well had been sunk ; and as a cure for the " priming," it 

 was suggested to try a minute quantity of sulpliuric acid to neutralise the 

 alkali. There appeared, however, to be a question whether the water from 

 the green sand was really completely excluded. 



ROYAL SCOTTISH SOCIETY OF ARTS. 



Feb. 26.— John Cay, Esq., F.R.S.E., President, in the Chair. 



The following communications were made: — 



" On a Method of Making Flint Glass for Optical purposes." By Mr. 

 William Cooper, glass manufacturer, Aberdeen. 



Mr. Cooper, in his communication, states as a known fact, that " crown 

 glass," a manufacture peculiar to this country, answers very well for optical 

 purposes ; but hitherto there has been great difficulty in obtaining suitable 

 flmt glass of a uniform density, and free from striae, wreathes, &c. ; and this 

 may be attributed to the excise restrictions formerly altogether preventing, 

 by heavy penalties, the necessary trials being made to produce a suitable 

 glass, and hence we were driven to France and Switzerland for a supply, 

 where no obstacles exist in the way of making it. The mixture given by 

 Mr. Cooper was stated to produce a glass suitable for optical purposes ; and 

 the excise restrictions being removed, and being possessed of materials and 

 every other facility for making it equally good, it is expected that the 

 manufacture of optical glass will be perfected in this country. 



The following recipes are given by Mr. Cooper for making good optical 

 flint glass : — 



Sand, well wflshod, dried, and sifted .. 601b. 



Oxide ot lead (!ll 



Purified catbouale of potash 15 



Saltpetre :^*5 



Cullet 15 to 20 



The specific gravity of this glass is 3'568, and of ordinary density. A 

 heavier glass is obtained by altering the proportions thus ; — 



Sand BOlh. 



Oxide of lead 63 



Purilied carbon^ite of potastl 14 



Saltpetre 3'25 



Cullet 20 



The specific gravity of this glass is 3'628. In both cases the cullet must 

 be of the same kind of glass. 



Before disposing of this communication, the Secretary was instructed to 

 write to Mr. Cooper to send specimens of optical glass made after these 

 recipes, or to communicate the names of opticians who bad used the same 

 and found it good. 



" Statements regarding the American Sam- Gin, for separating the seed 

 from tJie Cotton Fibres ; and as to the practicability of applying Steam- 

 Power to the Roller- Gin : (nid Description and Drawings of a Steam-Potcer 

 Roller-Gin." By Roebht Burn, Esq., Edinburgh. 



After describing Whitney's Saw. Gin, and assigning the alteration of cli- 

 mate as the cause of the failure to introduce it into the East and West 

 Indies, Mr. Burn, in explanation of the above-mentioned model, pointed out 

 that the application of steam-power to this, the only kind of gin adapted 

 for the cotton of those countries, was mainly wanting to reduce the price of 

 their produce to that of America, and, by an increased supply, to place the 

 cotton trade in safer foundation, and more secure agaiust the growing com- 

 petition of the United States. 



In support of this hypothesis, Mr. Burn adduced the past history of the 

 cotton trade, and the transfer of it from the East Ind.es to Britain by me- 

 chanical science and skill, in the application of steam-power to the spinning- 

 wheel and power-loom, which at first was slow, but sure in its progress. In 

 the United States, this mechanical skill is now carried to as high a pitch, 

 and hy the invention of the Siiw-Gin they are in advance of us, as no 

 similar machine has yet been adapted to the colton of any of the British 

 colonies. 



