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SCIENCE. 



THE AMERICAN SOCIETY OF MICROSCOPISTS. 



The third annual meeting of the American Society of 

 Microscopists, the largest representative body of miscros- 

 copists in America, will begin at Detroit, Mich., the 17th 

 day of this month (August), and will continue four days. 



The circular of the Society announces that the head- 

 quarters will be at the Detroit Female Seminary, No. 82 

 Fort Street West. Ample arrangements are being made 

 by the (local) Griffith Club of Miscroscopy for the com- 

 fort and convenience of its guests. Free accommoda- 

 tions are to be furnished the members and delegates of 

 the American Society at private residences, and the 

 noted hospitality of the citizens of Detroit will un- 

 doubtedly be freely dispensed to the visiting Society. 



The forthcoming meeting of the Society promises to be 

 the most successful yet held. Several valuable papers 

 will be presented, and new and original mechanism in 

 the construction of stands will be shown and described. 

 Also in the preparation of microscopic objects several 

 valuable and much needed improvements will be pre- 

 sented. 



The circular issued by the Society extends an in- 

 vitation to microscopists who are not yet members to be 

 present, also to join the Society, and participate in its 

 business, both scientific and executive. 



The last meeting of the American Society was held at 

 Buffalo, N. Y., one year ago, and the results, both in the 

 attendance and character of the papers read at that 

 meeting, were highly encouraging to the lovers of miscros- 

 copic work throughout the country. The influence 

 exerted by these meetings has been productive of a great 

 amount of good. Microscopic societies have been, and 

 are, forming throughout the country. In Pennsylvania, 

 New York, New Jersey, Michigan and other States good 

 working societies have lately been formed, and a corres- 

 ponding interest in scientific enquiry has been aroused. 

 This cannot but be valuable to the communities in which 

 these societies exist. This work must not be allowed to 

 cease, and therefore we trust the National Society may 

 have a long lease of life. 



Not only in stirring up an interest in scientific work is 

 the American Society valuable, but in original research 

 it will yet make its name known, as even now among its 

 members may be found many of the leading scientific 

 workers with the microscope in this country. The 

 officers of the Society, and of the Detroit meeting are as 

 follows : 



President, — Prof. Hamilton L. Smith, LL.D., of Geneva, N.Y. 



C Dr. W. Webster Butterfield, of Indianapolis, 

 Vice-Presidents, ) Ind., and 



( Mr. C. C. Merriman, of Rochester, N. Y. 



Secretary— Prof. Albert H. Tuttle, of Columbus, Chio. 



Treasurer— George E. Fell, C. E., of Buffalo, N. Y. 



(I)r. W. B. Rezner, of Cleveland, Ohio, 

 . Carl Seiler, of Philadelphia, Pa., and 

 . W. C. Barrett, of Buffalo. N. Y. 



Executive Committee 



THE TAY BRIDGE DISASTER. 



The report of the Court of Inquiry appointed to investi- 

 gate the circumstances of the fall of the Tay Bridge last 

 December, which was fatal to so many hundred lives, has 

 been made public, and the result is thus summarized and 

 commented upon by Nature : 



There appears to) be some difference of opinion amongst 

 the members of the court respecting the scope of the inquiry 



and the duties placed upon them by the Board of Trade, in 



1 on * [uence 01 which two separate reports appear together, 

 one by Col. Holland, Chief Government Inspector ol Rail- 

 ways, and Mr. Harlow, President of the Institute of Civil 

 Engineers, and the other by Mr. Rothery, the Wreck Com- 



missioner. The former report describes in detail the design 

 and method of erection adopted in the bridge, giving also a 

 description of the various alterations in the plan which were 

 rendered necessary as the work progressed. 



The bridge was 3,465 yards in total length, divided into 

 86 spans, and it was the central portion, of 3,149 feet in 

 length, which fell on the evening of December 28. As 

 originally designed, this central position was to consist of 

 lattice girders of 200 feet span, carried by brickwork piers 

 somewhat over 80 feet in height from high-water level, but 

 as the river bottom turned out to be different from what was 

 expected from the borings, and the difficulty of obtaining a 

 secure foundation greater, eleven spans of 245 feet and two 

 of 227 feet were substituted, and braced iron piers were 

 adopted in the place of brickwork, as imposing a less 

 weight on the foundations. It is these piers which at the 

 inquiry chiefly received attention, as there can be little 

 doubt that they were the immediate cause of the catastrophe. 

 The process of floating out and sinking the caissons 

 for these piers has already been described in these 

 columns, and so successfully was this — certainly the most 

 difficult and hazardous part of the undertaking — accom- 

 plished, that no suggestion of insufficient strength has been 

 made, and in the Report it is stated that there is nothing to 

 indicate any movement or settlement in the foundations of 

 the piers which fell. 



The caissons were lined with brickwork and filled with 

 concrete, on which was built a hexagonal pier of masonry 

 carried up to 5 feet above high-water mark. Upon this 

 pier was built up six cast-iron columns secured by holding- 

 down bolts to the masonry at the angles of the hexagon. 

 The columns were made up of lengths united by flanges and 

 bolts, and connected with each other by horizontal struts 

 and diagonal ties. The up-stream and down-stream 

 columns were each 18 inches in diameter, the remaining 

 four, 15 inches ; all were inclined 12 inches inwards at the 

 top. The piers thus formed were from 81 to 83 feet in 

 height from the top of the masonry to the under-side of the 

 girders. The diagonal bracing consisted of flat bars 

 attached to the columns by means of " lugs " cast on them, 

 being secured at one extremity by a screw-bolt passing 

 through the lugs and bar, and at the other by a strap pro- 

 vided with a gib and cotter for tightening up. The hori- 

 zontal struts consisted of two channel-bars bolted back to 

 back to a single lug on each column. 



It will thus be seen that all vertical load must be borne 

 entirely by the columns, and with the exception of the 

 small transverse resistance of the latter the whole of any 

 lateral pressure must be transmitted by the bracing. 



Whether as designed the bridge would have been strong 

 enough for its work if the materials and workmanship had 

 been good throughout is very doubtful, but, as carried out, 

 the evidence shows distinctly that it was not sufficiently 

 substantial for the heavy traffic and severe gales to which 

 it was exposed. When everything was tight and in good 

 order the bridge, at the time of its inspection by General 

 Hutchinson in Februarv, 1878, showed great rigidity under 

 the tests imposed by him, but by October of the same year 

 so much slackness had made its appearance in the bracing 

 that, besides the ordinary kcying-up by driving the cotters, 

 more than 100 packing-pieces about three-eighths of an inch 

 thick had to be introduced in different parts. 



Respecting the immediate cause of the accident the 

 Court states — "In our opinion the weight of evidence 

 points out the cross bracing and its fastening by lugs as 

 the first part to yield." This we believe the calculations 

 of Dr. Pole and Mr. Stewart, taken in connection with the 

 experiments of Mr. Kirkaldy, arc quite sufficient to estab- 

 lish. With a wind pressure of 30 lbs. to the square foot 

 on the windward girder and train, and half this amount on 

 the leeward girder, the stress on the tie-bar most severely 

 strained, would be i6'8 tons, or io"i8 tons per square inch ; 

 again, with a wind pressure of 40 lbs. to the square foot the 

 stress on the tie-bar would be 224 tons. Now, as Mr. 

 Kirkaldy's experiments, made by order of the court on some 

 of the tie-bars removed from the bridge, showed that the}' 

 broke with a load of from 19 to 23 tons, and the correspond- 

 ing lugs with a load of 23 to 25 tons, it is pretty certain that 

 the ultimate strength of this part of the structure would be 

 reached by a wind pressure of 40 lbs. to the square foot. 



