The Author. walls was considered to be part of the permanent work, and as such it was believed to be serving a useful purpose, and to justify its retention. As regards the width of the entrance to No. 3 graving-dock, it must be borne in mind that the dock was used by warships as well as by mercantile vessels, and the greater beam of the former required a much wider entrance than if only the latter had to be provided for. Warships up to about 80 feet in beam had made use of the dock. The width given to the body of the dock allowed better access of light and air than a narrower dock would have done.

Exception had been taken by Mr. Scott to the monoliths being formed with longitudinal and cross walls, but these contributed largely to the strength and rigidity of the structure, and the thinner walls of the shell permitted the digging to be done closer to the cutting edge; this facilitated the sinking of the monolith and reduced the amount of loading required. Attention had been drawn to the fact that there had been no appreciable rise in the level of high water at Glasgow since 1873. To some extent this might be due to the development of the river channel not having followed, as already stated, strictly scientific lines, in consequence of which the tidal flow might be impeded at places. There was also the fact of the relatively great increase since 1873 in the tidal compartment, provided by the docks and basins at Glasgow, which allowed the tidal influx to spread out over a larger area. The depths given in the Paper applied to the whole or the greater portion of the bottom width of the channel.

The general criterion that had been suggested by Mr. Scott, as to the depth of water that should be provided in the approach to a "first-class" port, namely, that the largest vessels, fully loaded, should be able to enter and leave at any time of the tide, was in the great majority of cases inapplicable. Wherever docks were closed by gates, opened near the time of high water only, the passage of shipping was regulated by that circumstance. At Glasgow, where the docks were all open, the great bulk of the vessels using the port were able to come and go between Glasgow and the sea at any state of the tide, and only the largest vessels required to accommodate their sailings and arrivals to the time of high water. The depth in the river must be a progressively increasing one to accommodate the increasing draught of vessels, and the Trustees had ever been alive to this, and by continuous dredging had kept the channel abreast of the requirements of the shipping frequenting the port.

23 March, 1915.

BENJAMIN HALL BLYTH, M.A., President,
in the Chair.

The discussion upon the Paper on "The Improvement of the River Clyde and Harbour of Glasgow" was continued and concluded.

13 April, 1915.

BENJAMIN HALL BLYTH, M.A., President,
in the Chair.

It was resolved-That Messrs. H. J. Deane, E. R. Dolby, C. Hitchcock, S. R. Lowcock, R. St. George Moore and H. F. Rutter be appointed to act as Scrutineers, in accordance with the By-laws, of the Ballot for the election of the Council for the year 1915-1916.

The Council reported that they had recently transferred to the class of

Members.

JOHN WILLIAM GRIFFITH, M.A., B.A.I. (Dubl.)

And had admitted as

WILLIAM AISTON.

LEONARD FYFE ALEXANDER.

JOHN FRANCIS SIDES, B.E. (Royal).

Students.

NORMAN ARCHER, M.Sc. (Manchester).

CLEMENT SPENCER BAINBRIDGE.

RALPH BLAKEBOROUGH,

HENRY JOHN BRETTON.

JOHN GUTHRIE BROWN.

THOMAS JOHN CHARLES.

CYRIL JESSE WITNEY CLOKE.

HAROLD COTTON, B.Eng. (Sheffield).

HUBERT COULSON.

ALEXANDER ROBERT EDINGTON.
GORDON RATTRAY FENTON.

PAUL FISHER.

WALTER FOster.

JOHN THOMAS FRASER.
WILLIAM FRANK GARDNER.
FREDERICK EDWARD GILLett.
CHARLES JOSEPH GRAY.
FREDERICK LANCELOT HARRIS.
NORMAN PILKINGTON HAYNES.
ROBERT RUSSELL HENDERSON.
JOHN YNUR HUGHES.
WALTER LEVERTON JESSOPP.
ALFRED ROY JONES.
THOMAS HENRY JONES.

WILFRED KIRBY.
WILSON LEGGAT.

EDWARD ARTHUR LISTER.
SYDNEY WILLIAM LUSCHER.
CAMPBELL GRANT MCKENZIE.
FREDERICK JOSEPH MANNING.
ROBERT FORBES MEFF.
ALEXANDER MICHIE, Jun.

MARK DOBELL MOTT.

ROBERT DAVISON MUIR.

SAYED GHULAM MUSTAFA.

ALEXANDER TWEEDIE NEWBIGGING.

EDWARD COLLINS NORTH.

ANTON POLLMANN.

EDWIN VALENTINE MURRAY POWELL.
JOHN SENIOR ROBSON.

LEONARD JOHN ROGERS.

GEORGE MONTAGUE TERENCE ROUSE.
ARNOLD RUDD.

JOHN ARTHUR SEARLE.
WALTER SUMMERBELL.
ALFRED EVAN THOMAS.
STANLEY THOMPSON.

ERIC ALBERT MARSHALL WALKER.
CLARENCE WEBSTER.

ARNOLD RIVETT WHITWORTH.

(Paper No. 4106.)

"On Impact Coefficients for Railway Girders."

By CHARLES WILLIAM ANDERSON, M. Inst. C.E.

For some years there has been little discussion of the subject of this Paper by The Institution, probably owing to the lack of recent experimental data which would assist in the formation of more positive conclusions than at present exist as to the proper allowance to be made for the dynamic effect of moving loads.

The subject is of especial interest at the moment to Indian Railway Administrations, in view of the very extensive programmes for strengthening or replacing girder-bridges which the rapid increase in the weight of rolling stock has rendered necessary.

The Author's intention to submit to The Institution a Paper on the subject of impact coincided with the desire of the Indian Railway Board to promote discussion of the matter; and, believing that his Paper would fulfil that purpose, the Board have favoured him with all the documents and experimental data which they have collected, in the expressed hope that they will help to ventilate a vexed question.

Any views which may be expressed in the course of this Paper are not necessarily those of the Railway Board or of any one railway-company.

In order that the discussion may be specially applicable to Indian conditions, it is proposed to commence by recapitulating the Government-of-India Rules as they now stand, and then to sketch briefly the history of their evolution. It is believed that this course will also provide a convenient basis for the consideration of the abstract question.