Passing Comments
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Road Surfaces Not WE have little cause to coinNow the Most Im" plain now of the durability portant Problem . of modern road surfaces, whilst
some, such as tarMacadam-, may be laid. and repaired in a fraction of the time formerly necessary._ The surfaces are In far better condition this summer than in previous years, although traffic has increased considerably; there are, however, still too .many changes which make themselves more apparent when what we may term the "skidding seakon " arrives. The modern problem is mainly one of accommodation and the improvement of the safety factor.
Possibilities of Metal A LTHOUGH the principle of Spraying Not Fully 1—kmetabspraying is well
Realized enough known to most of those
responsible for maintenance, it would appear that in many circles spraying, and particularly the wire process, is not being utilized to the extent it meriti. The one pistol will -use a wide variety of metals which make possible a multitude of uses. Rims sprayed with zinc will eliminate difficulties in the removal of tyres. Loose kingpins can be settled by metal sprayed inside the hole, without the removal of the axle: Pinking, prone to occur in certain engines, is prevented when the combustion
318 chamber is sprayed with copper or aluminium by which exhaust gases are radiated evenly. These and numerous other applications are possible with both
, convenience and economy, for the engineer and operator who investigate the matter can hardly, fail to discover many attractive features.
A Railway Story that WAITING recently ,at a busy is Fishy, but, Never
vv railway junction a reader theless, True . began to understand why traders prefer road transport Boxesof fish, thrown from the guard's van, burst as they struck the platform. A porter kicked their sides into position while streams of fishy water poured around. Into the resultant puddles bundles of magazines for a newsagent were thrown.
Armaments ProTT may come as a surprise to gramme Holds Up I inany to learn that some consNormal Production
mercial-vehicle manufacturers .
who are dependent upon outside supplies for essential components are already becoming a little disturbed about their Show vehicles. It is the fact, however, that supplies can by no means be relied upon, owing to Government demands, and the situation is not likely to be easier during the next 12 months.
ASPECIAL automatic switching device applicable to a variety of purposes, such as road signs, traffic lights, parking lights, etc., has been produced by Societe Tubest, of Fere-en-Tardenois, and is being handled by International Technical Developments, Ltd., Thames House, Millbank, London, S.W.1. Its action is based on photo-chemical reaction. If equal volumes of hydrogen and chlorine be exposed to sunlight the two gases combine instantly, but the rate becomes slower in subdued light, and ceases in darkness. The actual device consists of a bulb half filled with dilute hydrochloric acid and with two electrodes sealed through the Container, these being connected to an electrical supply. By electrolysis, hydrogen and
• chlorine are evolved. In the dark these do not combine, and a gas pressure is built up which bends a flexible membrane controlling a switch. Light reduces the pressure and the circuit is broken.
A Remarkable Switchcontrol Operated by
Light
Some Useful Pointers THE Exide chief engineer on the Work of A points out that many Batteries battery users fail to appreciate the inter-relationship of capacity, voltage and the specific gravity and volume of the electrolyte. The rated capacity of a cell is the amount it will yield en disCharge at a definite rate, down to a predetermined final voltage. The electrolyte is really a reservoir feeding lhe electrodes with the means for liberating their pent-up. energy. It is insufficient to have an atriple ,volume of electrolyte ; the initial specific gravity must be high. enough to ensure that the final gravity at the end of discharge is high enough to avert trouble. ; A battery may appear exhausted on discharge, but if left idle will partially recover, because the exhausted acid in contact with the active material is replenished, through diffusion, by sulphuric-acid-bearing electrolyte. This accounts for the higher capatity a intermittent discharge.