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THE CIVIL ENGLVEER AND ARCHITECrS JOURNAL. 



I OcTOBEB, 



mach greater efliciency with less weight of metal. The next point of im- 

 provement was in the engine ; in the construction of which, however, 

 there had been less change than in other matters. The former beam-engine 

 had been changed fi)r the direct-action engine, which was of various kinds ; 

 but the greatest change wliich had been made within the last ten years 

 consisted in tlie employment of greater quantities of wrought-iroa in the 

 construction of the engines, instead of the mass of cast. iron formerly used. 

 This was the only great change, — for the newest Halifax steamers were 

 still fitted up with the old-fashioned or lever-engines. The next improve, 

 ment consisted in working steam expansively to a much greater extent 

 than heretofore. It was only within the last ten years that they had 

 adopted this principle : the efl'ent of which was that instead of completely 

 filling the cylinder with steam, they filled only to the exteut of one-fourth 

 — a volume of steam not of course of equal density, but by which they 

 got two-thirds of the work done and at one-fourth of the cost. The next 

 improvement had been made in the paddle ; not so much, perhaps, in the 

 wheel itself — for he was still inclined in favour of the old paddle-wheel, 

 although for short voyages he admitted the advantage of the feathering 

 paddle-wheel which had been advocated by Mr. Price at their Meeting 

 some years ago, and he had then opposed him : — but of this by-and-by. 

 Another great improvement which had been made was the driving the 

 paddle-wheels faster. They had an old maxim which was, whereas a 

 good old horse going 2J miles an hour could not draw advantageously at 

 luore than 220 feet per minute, and that as the steam-engine was only a 

 substitute for horses, and reckoned as so much horse-power, it ought not 

 to go faster than 2J miles per hour — and Ibis one thing had kept them back 

 for half a century. He did not mean that the result should not be faster than 

 2J miles per hour, but that the piston should not rise up and down in the 

 cylinder faster than 2^ miles an hour, which was only four feet in a 

 second, while the motion of steam of 15 lb. was 1,100 feet in a second. 

 Fortunately, however, this old maxim had been abandoned, and the piston 

 now moved from 250 or 270 to 300 feet in a minute. For this improvement 

 they were indebted to no new principle, buttotheapplication of mathematical 

 principles of science. He now came to another great improvement, which 

 was the change in the formation of steamboats, which had been radical — 

 he meant the entire alteration of the form of the ships. A few years ago 

 steam-vessels which would go ten or twelve miles an hour were deemed 

 fast ships; now, however, we had attained a much higher rate of speed. 

 Vessels were then built on the old-fashioned principle that the water-line 

 should be nearly straight, and that the run of the vessel should be a fine 

 line, and that there should never be a hollow line, excepta little in the run 

 of the ship, but that there most certainly should not be any hollow line in 

 the bow, for there the water-line should be straight or a little convex. 

 Researches and inquiries were, however, made by a Committee of the 

 British Association as to the form which would enable the vessel to go 

 fastest ihrough the water. These inquiries lasted for years, and they es- 

 tablished, by a series of experiments, a set of very curious facts. For- 

 merly, every builder of ships had his notion of proportion ; some that the 

 length should be four times the breadth — others that it should be 4J or 5, 

 — and some went as far as to say that the length should be six times the 

 breadth, but these were deemed innovations ; so that although the propor- 

 tions of width as compared with breadth were said to be fixed ones, yet 

 strangely enough every one differed as to those proportions. Another 

 question was what part of the vessel should have the greatest width, and 

 it was generally thought that the greatest width should be nearest the bow. 

 Some daring persons had, however, put it back as far as the centre of the 

 ship. This was, however, the exception, and not the rule. Then there 

 was another great principle, which was that the bow and stern should 

 exactly balance each other, — that is, that the vessel should be equally 

 balanced; but the new rules which the British Association had established 

 were as follows : — They began by upsetting the old rule with respect to the 

 proportions which the length should bear to the breadth, finding that the 

 greater the speed required the greater should be the length, and that the 

 vessel should be built merely of the breadth necessary to enable the 

 engines to be put in, and to slow the requisite cargo. Then the second 

 great improvement made by them was that the greatest width of water- 

 line, instead of being before the middle, should be abaft the middle of the 

 vessel, and in fact two-fifths from the stern, and three-fifths from the bow. 

 The next great improvement was that, instead of having the bow broad 

 and bluff, or a cod's-head bow, for the purpose of rising over the wave, 

 you might have hollow water-lines, or what were called wave lines from 

 their particular form, and with that form the vessel would be propelled 

 with less power and greater velocity, — and also that instead of keeping to 

 the old fine run abaft and cutting it away you might with great advantage 

 have a fuller line abaft, provided it was fine under the water. Thus by 

 these improvements the form of the old vessel was pretty nearly reversed, 

 to the great annoyance of the old school, and the steamers were given 

 large and commodious cabins and after-hohls, instead of having cabins so 

 pinched in that you could hardly stand in them. Another heresy intro- 

 duced by the British Association was, that of the principle as to the 

 balance of the stern and the bow upon which they now rested ; but which 

 was founded in a most singular error, for they left out something which 

 was very material. They concluded that the wave acted equally on both 

 ends of the vessel in striking it ; but they did not take into consideration 

 the impossibility of this when a vessel was moving, not having taken into 

 calculation the velocity of the wave or of the vessel, and that from this 

 circumstance the concussion from a wave striking the bow would be a 

 »nost powerful one, while it could not be so with regard to the stern, be- 



cause if the velocity of the wave meeting it was fifteen miles, the shock 

 would be as of thirty miles ; and, therefore, it became most plain that the 

 bow would give the greatest resistance to the wave. He had examined 

 all the fastest steamers which had accomplished from fifteen to seventeen miles 

 an hour — and in smooth water eighteen miles an hour; and he would 

 venture to state that there was not one of them which accomplished fifteen 

 to seventeen miles an hour, which had not all these alterations in every 

 particular, and that the wave form and wave principle were now adopted 

 by all the great steam-ship builders, and that all the fast steamboats had 

 what was called the wave-bow. Now, of the eight boats on the Holy- 

 head and Dublin stations, if examined, it would be found that all of them 

 were built on these principles, although in some of them there was still 

 left a little of the old principle, some of the boats being made a little 

 fuller and more straight; and if any one would look at one of these boats, 

 it would be perceived that the moment they moved the very wave itself 

 rebelled against them and broke against their bows, — and that conse- 

 quently these were slower than any of the class ; and he gave the details 

 of their construction, — for which we have not space. All of them were 

 examples of the value of the form and the principles which the British 

 Association had advocated and introduced at a very early period in its 

 history. 



Mr. J. Taylor stated, that as Treasurer of the Association, he could 

 bear witness to the value of the efforts of the Association in this direc- 

 tion ; and he felt bound in justice to state that the credit Mr. Russell had 

 given to the Association was chiefly due to himself, as the individual who, 

 with the late Sir J. Uobinson, had conducted the iovestigatious on this 

 subject. 



" On Common Salt as a Poison to Plants." By W. B. Randall. 



The following notice is presented as being likely to afford a useful 

 practical caution to those interested in the cultivation of plants. In the 

 month of September last, three or four small plants in pots were shown to 

 the writer, nearly or quite dead ; and he was, at the same time, informed 

 that their destruction was a complete mystery to the party to whom they 

 belonged, and that Dr. Lindley had expressed his opinion, from the 

 examination of a portion of one sent to him, that they were poisoned. 

 Having searched in vain for any strong poison in the soil, and in the plants 

 themselves, he inquired more minutely into the circumstances of the case, 

 and found that these were only specimens of many hundreds of plants 

 both in the open air and in green-houses (but all in pots) which exhibited, 

 in a greater or less degree, the same characteristics. The roots were com- 

 pletely rotten, so as to be easily crumbled between the fingers ; the stems, 

 even in young plants, assumed the appearance of old wood ; the leaves 

 became brown, first at the point, then round the edge, and afterwards all 

 over ; while the whole plant drooped and died. At least, 2,000 cuttings 

 in various stages of progress, and 1,000 strong, healthy plants had been 

 reduced to this condition ; including different varieties of the fir, cedar, 

 geranium, fuchsia, rose, jasmiue, and heath. The sight of this wholesale 

 destruction, coupled with the fact that the whole were daily watered from 

 one particular source, suggested the conclusion that the cause of the evil 

 must reside in the water thus used ; and this was accordingly examined. 

 It yielded the following constituents, making in each imperial pint of 20 

 fluid ounces, nearly 'JJ grains of solid matter entirely saline, without any 

 organic admixture : — 



Carbonate of lime .. .. .. .. OflOO 



Sulphate ol lime .. .. .. .. 0"-lf!2 



Chloride ol calcium .. .. .. .. 0-200 



Chloride of magnesium .. .. .. *. 1*252 



Chloride of sodium .. .. .. .. €*906 



9-420 

 The mould around the plants and an effusion of the dead stems and 

 leaves also afforded abundant evidence of the presence of much chloride of 

 sodium. Further inquiry showed that the well from which the water was 

 procured had an accidental communication, by means of a drain, with the 

 sea ; and had thus become mixed with the salt water from that source, 

 and had been used in this state, for some weeks, probably from two to 

 three months. From about that time the plants had been observed to 

 droop ; but it was not until nearly the whole of a valuable stock hail been 

 destroyed, that any extraordinary cause of the evil was suspected. To 

 place it beyond doubt that the water was really the cause of the mischief, 

 twelve healthy fuchsias were procured from a distance and divided into 

 two parts ; half being watered morning and evening with the water in 

 question, and the others with rain water. In a week, tlie six plants 

 watered from the well had turned brown, and ultimately died, while all 

 the rest remained perfectly flourishing. Assuming from these facts, that 

 the common salt in this water was the chief cause of the results described, 

 it is proved that water containing about seven grains of salt in each pint 

 is, in its continued use, an efl'ectual poison to the weaker forms of vegeta- 

 tion ; or that when a .soil is continually watered with a weak solution of 

 salt it gradually accumulates in it until the soil becomes sufficiently con- 

 taminated to be unfit to support vegetable life. In either case an inter- 

 esting subject of inquiry is suggested — What is the weakest solution of 

 salt which can produce in any measure this poisonous effect? — or, in 

 other words, at what degree of dilution does the danger cease? For salt 

 is an important natural constituent of much spring water, quite indepen- 

 dent of any inlillration from the sea, as in this instance. Thus :— the 



