TRANSACTIONS OF SECTION G. 5O1 
means of microphotography has steadily developed during the last few years. 
The author has recently applied a photographic method for obtaining a record 
of the relation between the load and extension of metals right up to the break- 
ing point. The diagrams taken in this way show very clearly the peculiarities 
of the metals at their yield points, and also the load actually on the specimen 
at the moment of fracture. The combination of the two methods offers a 
promising field for research. Some photographic records and microphotographs 
were exhibited on the screen. 
3. The Humphrey Pump. 
By H. A. Humpurey, M.Inst.C.H., M.1.H.E. 
The paper explained the principle, theory, and construction of these pumps, 
and concluded with a description of the two most important installations—the 
plant at the King George V. Reservoir at Chingford, Essex, where five pumps 
each lift 40 million gallons per day to a height of 30 feet; and the scheme for 
draining Lake Mareotis now being carried out for the Egyptian Government at 
Mex, near Alexandria, where eighteen pumps are ultimately to be installed, each 
capable of lifting 100 million gallons per day to a height of 20 feet. 
4. The Stress Distribution in Short Compression Members. 
By Professors Coxrr and Fiuon. 
Short compression members are occasionally used for constructive purposes, 
but more especially for tests on materials like brick, stone, and concrete, which 
are almost invariably used in compression. In all such cases the mode of 
application of the load is an important factor, and its influence on the stress- 
distribution is known to be great. 
This is recognised in the testing of engineering materials, and care is taken 
to ensure as uniform a distribution of load as possible over the end faces of the 
loaded member. Occasionally these faces are ground to approximately true 
planes by means of emery wheels or the like, in order to obtain a uniformly even 
bearing, and when the size or material of the specimen makes this impracticable 
the specimen is often faced with plaster of Paris for the same purpose. 
A convenient method of investigating the stress at any point of a short com- 
pression member of rectangular section is afforded by the optical effects pro- 
duced in a transparent model, combined with mechanical measurements of the 
lateral changes produced by the load. 
In the experiments described in the paper a special form of compression- 
testing-machine was used, having one fixed pressure-plate, while the other has a 
slight frictionless movement in the direction of application of the load, and this 
latter is weighed by a system of levers. Experiment shows that a block of 
transparent material subjected to compression between steel or brass plates is 
never uniformly loaded owing to tangential stress at the planes of contact pro- 
duced by the lateral changes of the two different materials. If a very exten- 
sible material is interposed between the specimen and the pressure-plates of the 
testing-machine, a very marked effect is produced of a similar nature to that 
obtained when a fine-grained homogeneous stone is stressed between lead plates. 
Approximately pure compression-stress may be obtained when the com- 
pression-plates are of the same material as the specimen, and measurements of 
stress distribution in various cases were described and compared. 
5. The Artificial Electrification of the Atmosphere. 
By Sir Outver Lovag, I’. RS, 
6. Report on Stress Distributions in Ungineering Materials. 
See Reports, p. 200. 
7. The Stresses in Built-wp Columns. By H. G. 5. Dunurinu, M.Sc. 
