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THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[July, 



tries. From 1809, the period when the English protection system extended 

 in favour of Canada, the decline of the trade with England commenced, and 

 in the same proportion as the exports to England fell off, did the use of Bri- 

 tish manufactures decrease. Hamburgh and the German States also became 

 new markets for this doscription of Norwegian produce, and German manu- 

 factures superseded in a great measure those of England. A table was then 

 read, showing the great exports of Norwegian timber. The paper then 

 treated of the managment of forest in that country (Norway.) Much has 

 been said about the decrease of the woods in Norway, but it is generally ad- 

 mitted by those conversant witli the subject that the reproduction is as rapid 

 38 the consumption. The fishing trade is next in importance to the timber 

 market, fish being exported to a great degree (the paper here gave a list of 

 the various fish to be found in this interesting ccmntry,) all of which in- 

 creased V'ifh the exception of lobsters. In the last three years, since 1841, 

 the annual average exports have not much exceeded ,')00,000. The chief 

 market for salmon was Denmark. For several years the salmon trade was 

 verv prosperous, but of late it had been very limited. This was found to be 

 owing to immense shoals of sharks. The discovery was made by two ships 

 being sent out for salmon ; when eight ships were fittted out for shark 

 ■fishsng in 18J1, and 20,000 of these voracious animals were captured, and 

 their numbers did not appear at all diminished. Norway was increasing in 

 importations, especially in coffee, tobacco, cotton twist, and an immense 

 number of other articles which the paper enumerated ; and there was a great 

 probability of our trade with Norway Increasing from the impetus given to 

 trade by the revision of the tariff. The paper was very elaborate and ap- 

 peared to yield great satisfaction. 



Mechanics. 



Place of meeting— Lecture Room under Public Library. 



President— Sir George Rennie. F. R. .S. 

 Vice-Presidents— Professor Willis, F. R. S., Wm. Fairbairn, Sir John Guest, M. P., F. 

 Scott Russell, F. R. S., Edin. 



Secretary — Rev. W. T. Kingsley. 



Committee- John Taylor. F. R. S. Richard Roherls, C. E., Eaton Hodgkinson, F.R.S. 

 J. F. Baleman. C. E., J. Dent, P eter Claref Joseph Whitworth, C. E., J. Jessop, Rev. B. 

 M. Cowie, T. Cooper. 



A paper was read by Dr. Booth On a method of convi>rting Rectilinear into 

 Stotary motion. Ihe following paper was read by Dr. Greene. 

 Oil Mr.Nasmyth^s steam hammer for pile driving. 



Before entering upon the action of Mr. .lames Nasmyth's patent steam 

 pile driver, as many members may be present who have not heard my de- 

 scription of it at our last meeting, I shall with permission briefly advert to 

 to its principle, without entering into a detail of its construction. It con- 

 sists of a steam cylinder, closed at the bottom, but the top has openings to 

 allow the passage of air. A piston works in it, having its rod passing through 

 a steam tight aperture in the bottom. To this piston rod the monkey, or 

 driver, wliich weighs 1\ tons, is attached, and by which it is suspended. The 

 machine is worked by high pressure steam, which being admitted at the bot- 

 tom of the cylinder by the induction pipe raises the piston, and with it the 

 monkey attached to it. The instant it arrives at the height required, it closes 

 the induction pipe, and opening the eduction pipe (also at the bottom of the 

 cylinder,) the steam escapes, and the piston with the monkey attached to its 

 rod falls freely upon the head of the pile. A large heavy cap of iron with a 

 hole to allow tlie head of the pile to pass through slides between two upright 

 standards, and guides the direction of the pile. The monkey and cylinder 

 also follow the course of the pile, guided by the same uprights, between 

 •which they slide. 



I am highly gratified in being able to lay before the Association an account 

 of the action of the very ingenious machine of wliich I have just given a brief 

 outline. I extract the report from a letter from Devonport which I yester- 

 day received from my friend James Nasmyth, the inventor. In the first trial 

 with a part of the machine at the manufactory it drove a pile 14 inches 

 square and 18 feet in length 15 feet into the ground with 20 blows of the 

 monkey, the machine then working 70 strokes a minute; the ground was a 

 coarse ground embedded in a strong tenacious clay, performing this work in 

 17 seconds. The entire machine is now in full action at Devonport for the 

 embankment to be erected there to keep out the sea, and form an immense 

 wet dock to contain the royal steam navy. lie describes it as going far be- 

 yond what he had dared even to hope for, and that it is truly laughable to 

 see it stick vast 6G feet piles into the ground as a lady would stick pins into 

 her pincushion. The entire time of operations required to be performed on 

 each pile from the time it is floated alongside of the stage until it is em- 

 bedded in the solid foundation of slate rock is only 4J minutes. The great 

 stage which carries the machine, boiler, workmen, and everything necessary 

 trots along on its own railway like a wheelbarrow, it moves on the diameter 

 of a pile the moment it has finished the last. It picks the pile up out of the 

 water, hoists it high in the air, drops it into its exact place, then covers it 

 with the great magic cap, which follows it as it sinks into flie ground, then 

 thump goes the monkey on its head, jumping away 75 jumps a miuite. At 

 the first stroke the pile sank 6 ft., its advance gradaidly diminishing until in 

 the hard ground above the sound slate rock it was reduced to 9 inches. 

 Nothing can prove the superiority of the principle of Nasmyth's brilliant in- 

 Tentiou of getting his momentum by a heavy weight moving with small ve- 



locity, over the same momentum, as got on the old principle, by a light 

 weight moving witli great velocity, than the state of the heads of the' piles as 

 driven by each process. I beg leave to call your attention to this sketch of 

 two heads of piles, one 56 feet long driven by a monkey of 12 cwt, falling 

 from a great height, and making only one blow in five minutes, and requiring 

 20 hours to drive if; this, though protected by a hoop of iron, is so split and 

 shattered on the head that it would require to be re-lieaded io drive it any- 

 further. The other, although 66 feet long, was not even supported by aa 

 iron hoop, and the head is as smooth as if it were dressed ofl" with a new 

 plane. It was driven with a hammer 50 cwt. and only 3 feet fall, making "5 

 blows a minute, and was put in its place and finished in 4^ minutes. I beg 

 leave to observe that in addition to other great advantages of driving by a 

 heavy weight over tliat of driving by a light weight is the immense saving of 

 labour, or whatever nmving power is employed, ilomentum being the pro- 

 duct of weight multiplied by velocity, you may get the same momentum in 

 various ways by varying both the factors ; but where the velocity employed 

 is that produced by the action of gravitation the greater the velocity em- 

 ployed, the greater is the loss of power. Suppose for example we want a 

 momentum 16, a weight 8, with velocity 2 will give it, and let us suppose 

 that velocity created by the weight of falling from a height of 3 feet, we can 

 get the same velocity by employing a weight of 4, and velocity 4, but to 

 create that velocity by falling, the body must fall from a height of 12 feet, 

 or four times the former height, the velocities being only as the square roots 

 of heights ; now it is evident that it will require double the power to raise 

 41b. 12 ft. high as to raise 81b. 3ff. high, so that there is a loss of one half 

 of the power employed in the latter case. This new and powerful agent I 

 expect will produce great national results in the contemplated harbours of 

 refuge which are to be formed along our coasts, and the recovery of vast 

 tracts of land from the sea, and which it will now be as easy to effect, as, 

 before the operation of this new power, it would have been diflicult, and in 

 many instances impossible. I shall only add in conclusion that the site of 

 that great national work the Royal Steam dock at Devonport was actually 

 planned and laid out on the faith of the powers of the pile driver ; as infer- 

 red from those of its sister machine the patent steam hammer with whose 

 worderful performance the Admiralty had been previously acquainted, and 

 which is also the invention of the same talented individual to whom not 

 only his own country, but the most remote regions of the civilized world are 

 so deeply indebted. 



A meeting took place at Section A room to take into consideration the 

 best mode of conducting simultaneously the Magnetical and ileteorological 

 Observations, in all the first class observatories. The meeting was attended 

 by several distinguished foreigners interested in the question, and by Mr. 

 Airy, and other English philosophers ; Sir J. F. W. Herschelwas in the chair. 

 Mr. Airy objected to a proposal of three hours, and also of four, and pro- 

 posed a resolution as follows : — " That where it is found inconvenient or im- 

 possible to take the observations at every hour, they should be made every 

 two hours, and these hours should be the even hours of Gotfingen mean 

 time." This motion was assented to, and also another that mean Gottingen 

 time should be used. 



TERRESTRIAL MAGNETISM. 



The Astronomer Royal delivered a discourse in the Senate House, on the 

 recent progress of Terrestrial Magnetism. 



Sir J. F. W. IIerschel was in the chair. 



Mr. AiRv, the .\stronomer Royal, began by stating that he should treat 

 the subject in a large and general view, though it would be necessarily very 

 imperfect. He presumed every one knew the construction of the compass and 

 the properties of the mognetic needle, and explained the meaning of the 

 " dip of the needle," at Cambridge the dip at this time was 70 deg. from the 

 horizontal. The dip and horizontal directions were different at different parts 

 of the eajth. The horizontal force of the attractive power of magnetism was 

 determined by the vibratory motion given to a needle, by removing it by an- 

 other force from its own directive power; power would endeavour to restore 

 the needle to its true position, but the impetus gained in the action carried it 

 beyond the magnetic north, and thus caused vibration as of a pendulum, and 

 the horizontal force could then be determined by the number of vibrations ia 

 a given time. This much of magnetism was known at the beginning of the 

 of the present century, together with the fact that about the year 1600 the 

 needle pointed east of the nortb meridian, that soon after it pointed to west 

 of north, and increased in this direction until it attained an angle of more 

 than 23 degrees ; it is now so nearly stationary tliat it cannot be determinately 

 settled whether it will go farther westward or return ; suspicion was strong 

 that it was on the point of returning. The construction, or rather the mount- 

 ing of the present dip needle was explained; it has an axis at right angles to 

 its directive power, resting on knife edges, that is, steel exceedingly hard and 

 sharpened, or agate ; with this it was found that the dip could be determined 

 within a few seconds. It bad been discovered by Graham that the needle had 

 a diurnal oscillation, and that it mady a great western spring at 2 p.m., and 

 was most eastern at 8 a.m. aud 8 i'.m. ; this occurred with great regularity, 

 and attracted much attention, and the Astronomer Royal thought it might be 

 in some way caused by the sun. The next portion of the subject was on 



