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TRANSACTIONS OF SECTION G. 897, 
FRIDAY, SEPTEMBER 18. 
The following Papers were. read :— 
1. Report on the Effect of Wind and Atmospheric Presswre on the Tides. 
See Reports, p. 503. 
2. Report on the Calibration of Instruments in Engineering Laboratories. 
See Reports, p. 538. 
3. Description of General Features and Dimensions of the Tower Bridge. 
By J. Wore Barry, C.L., PLS. 
London Bridge built in 1280.—\ts dimensions.—The houses upon it.—Its im- 
provement in 1758: ¥ 
New London Bridge built in 1824 to 1831.—Its approaches.—Only one bridge- 
for metropolis till 1729, when Putney Bridge was built in spite of opposition of 
Corporation of London. 
Eight more bridges built between 1730 and 1830.—Development of South Lon- 
don and distribution of population.—Reference'to Thames Tunnel and Tower Sub- 
way. 
S eeoprolitan Board of Works proposed Bridge in 1879.—Proposal by private: 
company for Subway in 1883.—Subway of Metropolitan Board of Works in 1884, 
and duplex bridge.—Proposal for bascwe bridge.—Description and views of original 
design by Sir Horace Jones. 
Corporation of London apply for permission to build present Tower Bridge in 
1885.—Description of Upper and Lower Pool of Thames.—Temporary works for 
constructing the Bridge——Action of Government authorities and approval of the 
Queen.—Detailed description of piers and bascule chamber.—Mode of construction 
of substructure of piers.—The Caissons.—Mode of sinking Caissons.—Construction 
of pier within Caissons—The Abutments.—The opening span.—Its dimensions.— 
Mode of construction and weight.—Mode by which it is actuated.—The hydraulic 
machinery.—Pumping engines and accumulators.—Estimated wind pressure.— 
Requirements of Board of Trade and actual wind pressure.—Lifts for foot passen- 
gers.—The fixed superstructure——The masonry of the towers and differences of 
opinion asto employment of stone round the steel pillars of the tower.—The rollers 
carrying the chains.—Description of the chains and anchorages.—Total weight of 
steel and iron in the bridge.—Erection of superstructure.—Temporary bridge— 
expedients adopted.—The approaches.—Opening of the bridge in June 1894,— 
Estimates of river traffic as compared with actual traffic—The vehicular and foot 
traffic across bridge-—Cost of the bridge defrayed by Bridge House Estates Com- 
mittee —Acknowledgments of assistance rendered by various persons. 
4. On the Liverpool Waterworks. By J. Parry. 
Early history of the Liverpool water supply—Enyineering and chemical ideals 
of a century ago—Private enterprise and public spirit—Competition and its conse- 
quences—Bootle Company’s works—Harrington Company’s works—Purchase by 
Corporation—Schemes of 1846—Rivington scheme and its lessons—Investigations 
for additional supplies 1866-1880—Joint schemes for Manchester and Liverpool— 
Vyrnwy works—Filtration: Rivington and Vyrnwy—Experiences of introducing 
a new supply—Consumption of water—Supply of towns and villages on the lines 
of aqueduct. 
* 5. The Present Position of the British North Atlantic Mail Service. 
By A. J. Macrnnis. 
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