ELECTRIC LIGHTING AT THE FORTH BRIDGE WORKS. 883 
The preceding gives a brief description of the general arrangements 
which have been in use, so far, for the lighting, not merely of what may 
be termed the (comparatively) permanent part of the works (such as the 
offices, stores, workshops, &c.), but also for the actual operations on the 
foundations of the bridge itself. Shortly this last-named stage will be at 
an end, and the erection of the superstructure will necessitate, probably, 
far different arrangements—lights scattered widely and of a very port- 
able character. Then may perhaps come into play, as valuable adjuncts, 
those two other applications of the electric current—its utilisation in con- 
nection with storage accumulators, and for the transmission of power— 
objects the possibility of the future use of which led the author to adopt 
continuous current dynamo machines for the lighting by electricity of the 
Forth Bridge Works. 
The New Tay Viaduct. By Crawrord Bartow, B.A., M.Inst.C.E. 
[PLATE VII.] 
[A communication ordered by the General Committee to be printed in ewxtenso 
among the Reports. | 
ConsIDERABLE interest is attached to this undertaking, because of the com- 
paratively few viaducts of so great length crossing tidal water in such an 
exposed position, and also because of the fact that it is to replace the Tay 
Bridge, which was rendered useless by the memorable disaster of Decem- 
ber 1879. The Tay Viaduct is being constructed at the side of, and 60 ft. 
distant from, the bridge, the standing portions of which are used for the 
conveyance of men and materials, and in otherwise assisting the con- 
struction of the new work. The total length is 3,600 yards, i.e., a little over 
two miles. The number of spans is eighty-five, of dimensions varying 
from 50 ft. to 230 ft., and the height of the rails above high water where 
greatest—at the southern end—is 83 ft. At the four navigable spans 
near the middle of the river the height is 79 ft., which gives a clear head- 
way for shipping of 77 ft.; and from this point to the Dundee or north 
end there is a falling gradient of 1 in 114, which reduces the rail level at 
the Dundee end to about 25 ft. above high water. 
For the purposes of description the work may be divided into three 
parts—(1) the arching at Wormit, at the southern end of the viaduct; 
(2) the Esplanade spans, at the Dundee or northern end; and (2) the 
viaduct proper, #.e., that part which extends over the tidal water. 
1. The arching at Wormit consists of four arches of 50ft. span, with 
their abutments and piers—Nos. 1 to 4—-the whole being built of brick. 
Tn plan the width of the arching is equal to that of the viaduct at the 
‘northern end, but widens out at the southern end to accommodate the 
junction of the Newport branch with the Edinburgh main line. 
2. The Esplanade spans at the Dundee or north end of the viaduct are 
‘seven in number, between piers Nos. 78 and 85, and derive their name 
from the fact that they cross the existing and proposed extension of the 
Dundee Esplanade. Two of these spans—between piers 78 and 80—consist 
of brickwork piers and wrought-iron skew arches, built to suit the direction 
of the proposed Esplanade; next to these are four spans of wrought-iron 
girders supported on cast-iron columns, standing on granite and brick- 
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