7o 
SCIENCE. 
THE AMERICAN SOCIETY OF MICROSCOP 1 STS. 
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 
f 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. 
( Dr. W. B. Rezner, of Cleveland, Ohio, 
Executive Committee , < Dr. Carl Seiler, of Philadelphia, Pa., and 
f Dr. W. C. Barrett, of Buffalo, N. Y. 
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 
conse juence of which two separate reports appear together, 
one by Col. Yolland, Chief Government Inspector of Rail- 
ways, and Mr. Barlow, 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, [5 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 February, 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 keying-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, are 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'r8 tons per square inch ; 
again, with a wind pressure of 40 lbs. to the square foot the 
stress on the tie-bar would be 22 4 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 they 
broke with a load of from rg 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. 
