SCIENCE. 



7i 



And, in addition to this, more variation is to be expected in 

 the strength of the lugs, as some at least were admitted to 

 be of bad manufacture, and when the pier was most severely 

 strained it would be some of the worst lugs in the lower 

 tiers that would be the first to yield ; thus the samples taken 

 for testing would not be likely to embrace specimens of 

 the lowest strength, as these would probably have already 

 given way. 



Again, it does not appear necessary to assume a wind 

 pressure of 40 lbs. per square foot to ensure the destruction 

 of the pier ; the stresses above mentioned are due merely 

 to the statical pressure, and it can hardly be denied in the 

 face of the evidence respecting the details of the structure 

 that there would be a great deal of motion due to backlash 

 over and above the elastic yielding of the material. Thus 

 a much lower pressure would produce the effects calculated 

 for one of 40 lbs. per square foot. 



The principal conclusions arrived at by the court are that 

 there is no indication of settlement in the foundations, that 

 the wrought iron employed was of fair strength, though not 

 of high quality as regards toughness, that the cast iron was 

 fairly good, that the main girders were of sufficient strength, 

 and that the iron piers, though strong enough to sustain the 

 vertical load, were insufficient to resist the lateral action of 

 heavy gales from the weakness of the cross bracing and its 

 fastenings; that the railway company did not enforce the 

 recommendation of General Hutchinson by limiting the 

 speed of trains over the bridge to twenty-five miles per 

 hour, much higher speed being frequently run ; that while 

 of opinion that the fall of the bridge was occasioned by the 

 yielding of the cross bracing and fastenings, it might possi- 

 bly have been due to the fracture of one of the outward 

 leeward columns. 



Colonel Yollard and Mr. Barlow conclude by stating 

 " that there is no requirement issued by the Board of Trade 

 respecting wind pressure, and there does not appear to be 

 any understood rule in the engineering profession regard- 

 ing wind pressure in railway structures; and we therefore 

 recommend that the Board of Trade should take such steps 

 as may be necessary for the establishment of rules for that 

 purpose." 



Mr. Rothery, in his independent report, while stating that 

 there is an entire agreement between himself and his col- 

 leagues in the conclusions arrived at from the evidence, 

 goes further than they, and unhesitatingly apportions the 

 blame among the different parties concerned. On the recom- 

 mendation that the Board of Trade should establish rules 

 providing for wind pressure, he differs from his colleagues, 

 emphatically stating that it is for the engineering profession 

 to make them, and evidently regards the superficial charac- 

 ter of an official inspection as no great evil. 



Where French engineers have long adopted 270 kilo- 

 grammes per square metre, and many English engineers, 

 on the authority of Rankine, the equivalent 55 lbs. per 

 square foot, while nearly the same figure is used in America, 

 it seems strange that so much difference of opinion should 

 be found to exist ; but one thing at least is certain, that the 

 instruments at present in use for measuring wind pressure 

 are exceedingly crude and liable to error, and that until 

 these are improved and much increased in number there is 

 little chance of being on the spot when these excessive 

 pressures occur, or of truthfully recording them when met 

 with. 



Respecting the transfer of these responsibilities to a 

 Government Department, we believe that such apronstring 

 policy would be fatal to the profession of the civil engineer; 

 we would rather see the Board of Trade Inspection, which 

 at least is formal and superficial, relaxed than any attempt 

 made to increase its efficiency. The medical profession 

 does not require a fatherly department to watch over its 

 operations or give an opinion on an amputation ; why then 

 should the engineering profession ? It cannot be too clearly 

 understood that an engineering work cannot be success- 

 fully carried out by mere rule of thumb or even by the 

 copious use of " Molesworth" or "Rankine" ; each opera- 

 tion is to some extent a physical experiment, subject to 

 known laws, but under variable conditions. The physicist 

 and the engineer have already to a great extent established 

 the laws for themselves, but it remains for the scientific en- 

 gineer to carefully watch their operation, and thus gain 



that practical experience which will enable him to deal with 

 each special case as it arises. 



The conclusions we draw from the evidence and report 

 are that the design of the piers was most imperfect, cheap- 

 ness appearing to be the ruling element in every detail, a 

 cheapness too that must have been completely delusive, as 

 any money saved in first cost would soon, in such a rickety 

 structure, have been swallowed up in maintenance. At 

 nearly all points an absence of consideration for small de- 

 tails is most apparent, indicating probably that these were 

 intrusted to some subordinate, who failed to appreciate 

 their importance. 



It is very far from our object in this article to hold up 

 any particular individuals to blame for this disaster, but 

 we should like to point out on whom the responsibility 

 should rest if such a thing should occur again. 



It would be quite impracticable for the Board of Trade 

 to exercise such supervision over the selection of the 

 material and the execution and erection of a large work 

 throughout its progress, as would render its certificate of 

 any value ; we believe, therefore, that the undivided respon- 

 sibility should rest on the engineer. Any dishonesty on 

 the part of the contractor or his workmen— and we are 

 sorry to believe this still exists in some cases — could be 

 easily rendered hazardous by legal penalties. 



Doubtless with the keen competition of the present day 

 things must be " cut finer" than they used to be : but while 

 we would remove any arbitrary restrictions imposed by 

 Government on the judgment of those who ought to be best 

 able to appreciate the particular conditions of their own 

 work, we should be very sorry to see the introduction of 

 flimsy structures or reckless traffic arrangements without it 

 being understood on whom the responsibility rested in 

 case of failure. 



A letter recently sent to Professor Plantamour, director 

 of the Geneva Observatory, gives the details of a singular 

 phenomenon observed at Bonneville on the 25th of April. 

 It was noticed during a rain storm, that the drops of water 

 falling upon dark clothes, linen, umbrellas, left a dirty 

 yellow spot verging on brown. The matter was given over 

 to M. de Candolle, for investigation, who found that the 

 powder which colored the yellow rain, contained only or- 

 ganic elements of vegetable origin. Observed dry, or in 

 pure water, these debt is had mostly a yellowish color, but 

 some were colorless. They were generally formed of cells 

 of small diameter, upon the walls of which were granula- 

 tions consisting of the finest particles of the pulverulent 

 matter of the rain drops. The advanced state of disaggre- 

 gation of all these vegetable debris, did not allow of the de- 

 termination of their origin ; but the minuteness of the cells 

 seemed to indicate that they belonged to young tissues. 

 Amongst the fragments, with form so varied and irregular, 

 were found some spores of cryptogams, but no grains of 

 pollen\vere met with. 



M. Dines has calculated that the amount of dew deposited 

 on the ground in the course of a year would be represented 

 by a layer of water about 40 millimetres (1.6 in.) in height, 

 equivalent to 40 litres per square metre. 



The Royal Society of New South Wales now numbers 430 

 members, exclusive of honorary and corresponding mem- 

 bers. Mr. G. Bentham, Dr. Darwin, Prof. Huxley, Prof. 

 Owen and Sir. J. D. Hooker have been elected honorary 

 members, and Mr. R. Ethcridge, jun., a corresponding 

 member. The Clarke memorial medal for 1878 has been 

 awarded to Prof. Owen, for 1879 to Mr. G. Bentham, and 

 for 1880 to Prof. Huxley, for their contributions to palaeon- 

 tology, botany and natural history of Australia. 



