1850."] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



277 



double the number of men that could by any possibility work at 

 the crane. 



This suggests the possibility of a very considerable advantage 

 to railway companies, by the use of the proposed engines, as tlie 

 blowing cylinders for compressing the air might be attached to 

 the end of the piston-rod of any of the small-sized engines now 

 laid up at several stations, and the air conveyed to the various 

 cranes, to which cylinders might be attached for about 25/. per 

 crane, without disturbing the ])resent arrangement for the use of 

 manual power in cases of emergency. The saving of manual 

 labour by such an arrangement will be best estimated by the 

 managers of goods departments, some of whom are amongst the 

 members, and with reference to the mechanical application of the 

 power, the writer hopes to have the pleasure of presenting the 

 Institution with another paper at some future meeting. 



At the conclusion of the reading of the paper, several questions 

 were put to Mr. Slate, and which he answered. He stated that 

 he had used fans made according to Mr. Kuckle's principle, and 

 could speak to their excellence and superiority; they were tlie 

 least e.vpense in construction, being made with light wood arms, 

 and he had obtained from 4| to 5 oz. per square inch pressure with 

 them. He had tried both the cylinder-blast and the fan-blast for 

 melting iron, and indeed had them both now in use ; but he was of 

 opinion the cylinder-blast was decidedly the best for the purpose, 

 as the fan-blast caused the lining of the cupola to burn away 

 quicker, and also consumed a larger proportion of fuel. He had 

 found they could not blow so continuously with the fan-blast, and 

 required to stop more frequently for repairs of tlie lining than 

 with the cylinder-blast. The pressure of the fan-blast was iu)t 

 sufficient to carry it through the burden, so that the passage of 

 the air was more at the sides of the cupola, which caused the 

 lining to be cut away, and hence he considered the cylinder-blast 

 was the best for melting iron; and though it might not be so cheap 

 at first cost, there was no doubt of its ultimate economy. In the 

 thousands of tons which he had melted, he had been unable to 

 detect any difference between the quality of iron made under the 

 influence of the fan and that made by the cvlinder-blast. The 

 pressure with the cylinder-blast was about 3^ lb. per inch at the 

 cupola, and they had six 1-inch or l|-inch tuyeres. In the case of 

 the fan, they had two tuj-eres about 6 inches in diameter. They 

 used best Durham hard coke, because light coke was useless with 

 the cylinder-blast, which would blow it away. 



Mr. Davies said, he made an exhauster that had been used 

 extensively for blowing copper-melting furnaces, but he believed 

 the fan was preferred, though it gave less pressure of blast. 



Mr. Robinson thought the fan-blast was best for a cupola, and 

 he could not see the reason why the cylinder-blast should not 

 injure the sides of the cupola more than the fan-blast, because it 

 had greater pressure, and must have more power to force its way 

 through to the opposite side. 



Mr. CowpEK thought there would not be any greater destruction 

 of the lining with the fan-blast, unless there were some otlier 

 cause ; the circumstance of blowing with six tuyeres in the one case, 

 and only two in the other, might cause a difl^erence. At the Lon- 

 don Works the cupola was blown with a fan-blast, and had two 

 10-inch tuyeres at 5 oz. pressure, hut they did not find the sides 

 cut away ; on the contrary, witli some trifling repairs each morning 

 before starting work, the lining of the cupola lasted for many 

 weeks. 



Mr. W. Smith remarked, that he did not know any instance of 

 the fan being applied to blast furnaces in that district, and it was 

 for those more particularly that Mr. Slate's engine was proposed ; 

 the question raised by the paper, was whether in the case of blast 

 furnaces it was better to employ a small cylinder at a high velocity, 

 or a large cylinder at a slow speed. This small blowing engine 

 was proposed to supersede the ponderous machines which were 

 employed for the purpose at the blast furnaces ; he considered it 

 was an important suggestion, and he saw no reason why it should 

 not accomplish the object intended. 



Mr. CowpER was of opinion that the proposed quick motion 

 would give a more regular blast, wliich was a matter of great im- 

 portance as affecting the make of iron ; but it was a question 

 whether the great speed at which it was proposed to be worked 

 would not injuriously affect the durability of the v?orking parts of 

 the engine. 



Mr. M'CoNNELL did not think there was reason to fear any 

 serious objection from that cause, when it was borne in mind that 

 the piston of a locomotive engine frequently worked at the velo- 

 city of 800 feet per minute, and the proposed engine would be sta- 

 tionary instead of locomotive. 



THE TUBULAR BRIDGES. 



The Sntnnnia and Conway Tubular Bridges; with General In- 

 quiries on Jieams, and on the Properties of Materials used in Cnn- 

 striietion. By Edwin Clark, Resident Engineer. Published 

 with the sanction and under the supervision of Robert Stephen- 

 son. London: ^V'eale. 1850. 



The Tubular Bridges may now be supposed familiar to all, and 

 in taking up a book on the suliject, however important, we liave 

 some fear lest what we say, as being supposed to be on an old and 

 known subject, should not be listened to. The event is not near 

 enough to have the prestige of novelty: it is not yet far enough 

 for curiosity again to rise as to the actors by whom brought about, 

 and the circumstances attending it. Our reading of Sir. Edwin 

 Clark's book, however, has heightened our feelings; and though 

 in the pages of this Journal we have over and over again written 

 of the Britannia Bridge, we are not without hopes that our readers 

 will go with us in reviewing, on this the first complete opportunity, 

 the history of one of the greatest works of modern times, of a 

 great monument of our days, which, notwithstanding the sneers of 

 those who can properly appreciate neither antiquity nor the present, 

 are more fruitful in great moral events,and in vast physical exertions 

 than the world has yet seen. Many of us stand but as flies upon the 

 axles ; but as the wheel of Time's car runs swiftly on its way, 

 the wonders of bygone ages are quickly surpassed, and events, 

 each in itself the worthy subject of a history, are crowded before 

 us. When Alexander wept that he had no more worlds to conquer, 

 when Napoleon, greater still, thirsted for victory in Russia, or 

 even when he was tottering to his fall, the world was not so much 

 moved as now; for though the fate of single nations might waver 

 under the beam, the lot of mankind and the welfare of beings yet 

 to be born was hardly at stake. The revolution which has shaken 

 Europe, the sudden chance which has unlocked the golden stores of 

 California and opened a new world in the Pacific, the spreading 

 influence of the older English in China and Hindostan, and the 

 southward march of the two great English races to grasp the lord- 

 sliip of America, are events which would have dazzled the older 

 historians, and awakened the inspiration of a Thucydides, Livy, 

 Gibbon, or Niebuhr; but these events have not come alone. Kings 

 and nations, we know of old, can rise and fall; but time and space, 

 eternal in their laws, are now made sensible to us under very 

 different conditions. Every day we are made more and more aware 

 of the miglity influence of those applications of steam and elec- 

 tricity, by which the ends of the earth are being brought together, 

 and the most distant lands drawn within our reach. In suc!i mighty 

 operations it is that the man of science is made sensible how much, 

 by well-directed exertion, he may influence the destiny of man- 

 kind; and even the humble mechanic is called on to take part iii 

 these great actions. This is one — not the least important — of the 

 new aspects under which the world appears. Plato might strive 

 to influence statesmen; Aristotle gain the ear of Alexander; 

 Seneca train up a Ca?sar and find him a Nero; Bacon vindicate the 

 claim of philosophers to political influence; but such men could 

 never hope successfully to overcome the stubbornness of their 

 instruments, the chances of education, the vicissitudes of party 

 intrigues, or the disasters of barbarian warfare. It is by giving 

 less predominance to speculative science, and a more practical 

 turn to the labours of students, old and young, that a change has 

 been produced ; and the modern historian must attribute as great an 

 influence to a Watt, Trevithick, or Stephenson, as the older his- 

 torians to Socrates, Aristotle, and Bacon. It is not that morals have 

 lost by this change : it is that they have gained by the application 

 of intellect to practical results, instead of the elaboration of a 

 Republic, a Utopia, or an Oceania; and the contrast of the two 

 systems does not rest on a bright image of tlie present, and a dim 

 remembrance of the past, for we liave tliem face to face by sum- 

 moning a Kant, Fichte, and Hegel. 



If, however, the change is now most apparent, it has not been 

 suddenly brought about, for the foundation is what Bacon laid 

 and Newton worked upon; and the superstructure shows ino^t 

 now, for the foundations are deep. In proportion as this practical 

 system is carried forward, so must the share of the engineer be 

 greater, and the influence of the practical man be increased; and 

 the mechanic will hereafter seek that ])articipation in great deeds 

 in the vvorkshop, for which his fathers shed their blood on the 

 battle-field. Injthejpresence of the moral results that are obtained, 

 the ambition of the engineer will take a nobler direction; and 

 works will be carried out from motives of humanity, the magnifi- 

 cence of which would never attiact capital, nor allow of a profit. 



