348 SECTIONAL TRANSACTIONS.—A. 
separation of the rare isotopes of oxygen respectively carbon has been 
reached till now. This may be due to the adsorption of these gases in the 
porous tubes and at the glass-walls. 
Dr. G. W. C. Kays, O.B.E—Noise. (Experimental lecture followed 
by discussion) (11.30). 
Since its York meeting in 1932 the British Association has been alive to 
the many indications in the country of awakening general and industrial 
interest in the very old problem of noise and its abatement. The two major 
factors to be reckoned with at the present time are doubtless noisy road 
transport and noise-transparent dwellings. The volume of road traffic 
continues to expand and large sections of the population are now electing 
to make their homes in close three-dimensional packing in structures of 
which the designs and materials are pre-eminently favourable to the trans- 
mission of both air-borne and structure-borne noises. 
The Ministers of Transport and Health have set up noise committees to 
deal with motor vehicles and flats respectively, and both bodies have turned 
to the National Physical Laboratory for assistance. The British Standards 
Institution has very recently specified standards dealing with noise measure- 
ment ; and the great railway and aircraft companies are giving much atten- 
tion to the problem of reducing the background of noise for their travelling 
patrons. 
The cardinal principle of noise abatement is to reduce it at the source, and 
to this end the co-operation of the engineer is imperative in very many cases. 
Should noise reduction at the source be impracticable, one must interpose 
noise barriers, and in this connection much study is being directed to the 
elucidation of the primary factors which make or mar the soundproofing of 
floors, walls and windows. The last line of defence against noise is the 
judicious placing of surface absorbents which may assist in appreciably 
lowering the noise level in a room, whether of internal or external origin. 
Monday, September 9. 
Joint Discussion with Section G (Engineering) on Lubrication (Section A 
room) (10.0). 
Mr. J. H. Grsson.—Introduction. 
Adequate lubrication is the life-blood of every slider bearing, and, con- 
versely, all successful bearings, i.e. those which run with the minimum 
frictional loss, are designed and constructed to make the best use of the 
lubricating medium. A suitable oil may be regarded as the indispensable 
link in the mechanism. ‘The elements of bearing design consist in so 
arranging the several parts that oil, in ample quantity, but not necessarily 
under pressure, is fed in between the relatively moving surfaces, where it 
can be automatically entrained by its natural adhesion to the shaft or collar, 
then rejected and replenished ad lib. by the action of the bearing itself. 
The tapered clearance space existing in journal bearings facilitates the 
entry of the lubricant, and an internal pressure is generated in the oil film 
equal to the bearing load. The oil becomes heated, due to the resistance 
set up by the shearing action of successive layers. This heat is dissipated 
by radiation from the outer surface of the bearing or by cooling appliances— 
water-jackets or coils. In extreme cases the oil used is circulated through 
an external cooler. 
