438 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[November, 



Papers on suhjicts convec/td icith the Ditlks of the Corps of the Royal 

 Engtmers, Vol. '3. — London, Weale, 1S39. 



Thk volume before us keeps up the reputation of its predecssors, 

 and indeed with very little zeal on the ])art of the Members of the 

 Corps, it cannot fail to be otherwise, as they have such excellent op- 

 portunities of observing works executed or in progress, and for making 

 experiments, hi this latter career their services towards professional 

 literature might well be much greater, and we confidently anticipate 

 important results from the spirit of inquiry which these volumes in- 

 dicate. 



This volume may very easily be divided into two portions, the first 

 purely military, and the other immediately coimected with civil en- 

 gineering. 



The first two papers are on the lines of Torres Vedras, Cadiz, both 

 bjf officers of the name of Jones. Both are valuable, and the first par- 

 ticularly well drawn up. 



The paper on the model-towers approved by Napoleon, has been 

 already given in Muller's and other military works, but never hitherto 

 so completely. 



The fourth enters into minute details of the demolition of some of 

 the old works at Sheerness. 



Lieut.-Col. R. Thompson contributes a paper on furnaces for heat- 

 ing shot, with some remarks on their application to steam navigation. 



The sixth paper is on the fortification of Fosen. 



The report on Beaufort Bridge by Lieut. Nelson is a well arranged 

 plan for a bridge over the torrent river Kat, at Graham's Town. It 

 consists of a timber bridge of 3 arches, tiO feet span from centre to 

 centre of each pier, with a rise of 5 feet. The author states that he 

 took his idea of the construction from a sketch he made "of a prettily 

 contrived adaptation of the Prussian beams to a light foot-bridge of 

 nearly 100 feet span, with a central rise of about 6 ieet," when he was 

 in the Rhenish provinces in 1S34. The construction appears exceed- 

 ingly economic, and at the same time possessing ample strength; the 

 design also shows how architectural effect of a pleasing character may 

 be introduced even into a timber bridge, hi the design before us, we 

 have the piers in the bold Egyptian style which look remarkably well, 

 their height being upwards of 40 feet. 



The eighth paper contains a rough sketch by Lieut. Nelson, of an 

 admired suspension bridge over the Lahn at Nassau. 



Lieut. Denison's description of some of the works on the Rideau 

 Canal afibrds but too strong a proof of the manner in wdiich the public 

 money has been vvasted in ignorance and absurdity, and a striking ex- 

 ample of the inefficiency of government education and controul. With 

 timber at hand, the platform and wing walls at the entrance to the 

 lock, instead of being protected with sheet piling, are formed of large 

 stones, so as to ensure the destruction of the works. A great deal of 

 time and money seems also to have been wasted on ridiculous plans 

 for opening the lock gates. 



Another paper by Lieut. Nelson is also a foreign contribution, and 

 gives a description of the mode of bending timber in Prussia, to wliich 

 we shall hereafter have occasion to refer. 



The eleventh paper is of American origin, and describes the coffer 

 dam used in the construction of the piers of the Alexandria aqueduct. 



The twelfth is a description of a one-arch wooden bridge of i05 

 feet span at Paradenia, in Ceylon, thrown over the river Mahavillanga, 

 in which an interesting account is given of the difficulties contended 

 with. It shows too one of the causes of failure in government works, 

 for here it seems the Engineer's department constructed the abut- 

 ments, and the Quartcr-ma>ter general's the arch. 



The thirteenth paper describes a series of bridges erected across 

 the river Ottawa, in Canada. An account is given of a wooden bridge 

 of 21- feet span, which would have been very extraordinary and very 

 useful, had it not required a number of chains and ropes to keep it 

 from falling to pieces. It is singular that most of the descriptions of 

 works executed under military superintendence contained in this 

 volume are such as to be far from giving a satisfactory opinion of this 

 mode of conducting public works. 



The fourteenth paper is a new barometer invented by Mr. S. B. 

 Hewlett. — The next paper is on ascertaining the height of mountains. 

 Lieut.-Col. Reid's communication " Vn t/ie Optraliou if -'Salt Water 

 o» Iivn" we give below. 



" Considerable attention has been given of late to the effect which 

 saltwater produces in corroding iron; in consequence of that metal 

 being now used for facing wharfs, and other works exposed to the sea. 

 Some (lapers have been published on the subject, but their object has 

 been, 1 believe, only to ascertain the durability of iron as a material 

 when in contact with salt water. 



" 1 am not aware that public attention has ever been directed to 

 the curious change which takes place when iron, in contact with sili- 

 cious pebbles and other stones, is immersed in salt water. 



" My attention was first drawn to this subject from a desire of ac- 

 quiring a better knowledge of those laws of Nature which regulate 

 the cohesion of solid particles ; and from a conviction that the studv 

 of these laws would afford the best means of improving our knowledge 

 for practical purposes. 



" Almost every one has observed pebbles adhering to old anchors 

 which have long lain under the sea. Engineers who liave had to re- 

 move piles from sea walls or harbours have also noticed similar effects, 

 for the iron shoes at the points of the piles have generally a mass of 

 pebbles strongly incrusted around them. Even in wdiat we call fresh 

 water, (but which on analysis always is found to contain salts in solu- 

 tion,) this effect in a smaller degree is observed. 



" Having had occasion to reset part of what are called breakwaters 

 at Portsmouth, which are covered every tide by the sea, I was there 

 enabled in many instances to notice the effects here alluded to. Some 

 of file examples afforded beautiful specimens, and of several varieties, 

 of the carbonates of iron of perfect forms. When examined with a 

 powerful lens very delicate needle crystals were often distinctly visi- 

 ble ; these last which I observed were white. Those resembling car- 

 bonates of iron varied from black to brown, and to bright yellow : some 

 of the browns were of a very rich colour. These specimens were not 

 found at Portsmouth only ; at Hurst Castle planks of considerable 

 dimensions, wdiich the gales had broken from the groins, were found 

 firmly incrusted with silicious pebbles. It was not at first easy to dis- 

 cover from what cause the pebbles adhered to the wooil, but on sawing 

 a plank longitudinally it was found to have heen driven full of iron 

 scupper-nails. The flat heads of these nails were almost touching 

 each other; the heads had nearly disappeared, and in their place a 

 black shiny crystalline matter had been formed, which firmly united a 

 layer of pebbles to the plank. The opinion I formed on this was that 

 voltaic action takes place betvi'een the metallic iron and silicious 

 pebbles when inunersed in sea water. If this be the case, we can 

 scarcely doubt but that something of the same nature will occur be- 

 tween iron and other stones, when similarly placed. Part of the 

 breakwaters at Portsmouth were set with very thin sheet iron, between 

 blocks of Swanage stone, as an experiment : in a month afterwards, 

 sanil and small pebbles were found firmly fixed between the iron and 

 the stone ; and black crystalline matter, such as had been found at 

 Hurst Castle, appeared forming, and the experiment, as far as it has 

 been observed, seemed satisfactory. 



" After thus setting the breakwater with stones, alternating with 

 plates of sheet iron, I observed that Mr Cross had previous y pursued 

 studies somewhat similar, and that he was satisfied that iron, when in 

 contact with silex in a fluid medium, exhibits electric phenomena. An 

 observation to this etTect will be found in Mr. Leithsad's work on 

 electricity. 



" The subject of the formation of crystals by voltaic electricity, 

 which is one of great interest, is now making considerable progress, 

 and the object of this paper is to endeavour to show that the pursuit 

 of the study may be practically useful when applied to hydraulic 

 works; and that it well deserves to be ascertained whether plates of 

 thin iron, alternating with stones, and placed under the sea, will not 

 be found to form solid rock, with crystalline veins. Mixtures of iron 

 filings, s.uid and gravel, let down to the bottom of the sea through 

 tubes, might perliaps consolidate and form a stable foundation for 

 light-houses, and other works for which it is very difficult to form a 

 base. 



" Those parts of the Portsmouth breakwaters set with the thin sheet 

 iron will be found between the saluting battery and the spur redoubt, 

 and are visible on close inspection. The experiment has been varied, 

 somewhat in the manner above alluded to, by authority of the Ad- 

 miralty. Unserviceable iron water tanks from ships of war have been 

 filled with gravel, mixed with iron turj ings and a small quantity of 

 lime, in the construction of a groin opposite to Haslar Hospital. The 

 greater part of this groin will be covered by the tides; and thus a 

 good opportunity will there be afforded of observing the effects of 

 iron in contact with pebbles when immersed in salt water." 



We must defer Colonal Fanshawe's Report on the effects of tropical 

 climates upon Yorkshire paving. 



The following Report by Captain Streatfield " On the Wood Pave- 

 mmt in the Stab.es at Brighton" is so interesting at the present moment, 

 that although at some inconvenience, we feel obliged to call the attention 

 ol our readers to it. 



" Sir — In rej)ly to your letter, dated 17th u't., respecting the ex- 

 perimental pavement tried in the cavalry stables at this place, I now 

 send an extract from the officer's diary, written by Captain Alderson, 

 descriptive of the wooden block paving proposed anil executed by 

 him in January, is38. The alterations suggisted by Captain Aider- 

 son of making the f.iU 2 inches instead of -1, and the grooves | of an 



