OPINIONS FROM OTHERS.
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The Editor invites correspondence on cal subjects connected with the use of commercial motors. Letters should be on one side of the paper only and typewritten by preference. The right of abbreviation is reserved, and no responsibility for views expressed is accepted.
Sale of Newspapers.
The Editor, THE COMMERCIAL MOTOR.
[1004] Sir,—May I be permitted to occupy a small part of your space in .drawing the attention of readers of newspapers, magazines, etc,. to the provisions of what is known as the "No Returns" Order, which becomes effective. on 24th June 1 TheOrder may be described askan attempt to crystallize the demand and permit of an adequate, but not a wasteful, supply. Under it, distribution of the publications mentioned upon sale or return terms is prohibited. Readers will therefore serve their own convenience 4 and k_avoid certain disappointment by ordering beforehand .what they require. _ They will also help out the retail newsagents, a deserving and useful body, whose business would otherwise be disturbed to some degree by this Order.. Lastly, they will contribute to economy in the consumption of paper, which is wisential in the national interests, in view of the shipping situation.
H. A. VERNET, Controller. Department of the Controller of Paper, 23, Buckingham Gate, S.W. 1.
Suction Gas as a Motor Fuel.
The Editor, THE COMMERCIAL MOTOR.
[1605] Sir,—We have. read •Mr. F. E. Raymond's criticisms of your original article on " Suction Gas as a Motor Fuel, and submit the following-comments in case able adverse criticisms should tend to stifle progress. It is noted that by -the end of his article he had dropped into a more philosophic frame of mind than at the beginning. What/ strikes 'as most in the article is that the criticisms are based on a rigid interpretation of cornmon practice. He states that there must be a castiron door for clearing -purposes and a cast-iron vaporizer over the top of the fuel bed, and that "any reduction in the diameter of the furnace is not. allowable "because of the higher air velocities induced.
When We wrote you on the 29th ult. [This contribution appears in the centre page of this issue.—En. " C.M.1 we knew of these aspects of gas producers, but had already broken through these "musts." It is never safe to dogmatize. Take, for example, his reference to the diameter of the furnace. The assumption is that a four-cylinder high-revolution engine with its multiple suctions will induce the same air velocities and fuel temperatures as a single-cylinder long-stroke slow revolution engine of the same power. • On reflection it will be seen that the velocity will be less in the former case, and that fact of itself tends to permit a reduction of diameter of the generator—how much, however, is only determinable by experiment. But, in our system, we defeat the argument on totally different lines, leaving the above point to reveal itself in 'our favour later.
Of course, cylinder diameters may have to be increased slightly to allow for lowered gas values, but that is a secondary consideration in view of the fact that " producer _gas is the cheapest known fuel."
Mr. Raymond. states the truism that "there are little troubles connected with gas producer plants which occasionally puzzle the most experienced men." The same truism applies to such details as the.earburetter and ignition system of the petrol plant. Like all engineering products, gas producer plants respond to commonsense supervision. Recently, we visited a plant of. 100 h.p. which was running night and day without trouble, although the generator casing, was cracked top and bottom and, otherwise, acting contrary to its design. Had the makers seen it they would have done some furious thinking, but the plant was the pride of the attendant. if a steam boiler had its constitution so neglected it would have failed.
We had considered all the points raised by Mr. Raymond and have in hand a solution of the difficulties Mentioned. The gas generator was the great difficulty, the other items being simple in comparison.— Yours faithfully, STEwARTS GAS PRODUCERS CO. Glasgow. JOHN STENvART.
Pneumatics for Heavy Vehicles.
The Editor, THE COMMERCIAL MOTOR.
[1608] Sir,—I was interested in the leading article in your issue of the 23rd ult., in which you put forth claims concerning the use of pneumatic tyres for a heavier class of vehicle than that to which they are at. present fitted. There arc undoubtedly many points in favour of such a scheme, but I think it should be borne in mind that either twin tyres should be fitted or some 'means of warning to the driver should be embodied in the event. of a puncture or a gradual deflation occurring, which might result in some cases to serious damage to both tyres and tubes. I suggest some form of whistle system should be fitted to the tyre, and I believe this has already been tried in some quarters ; or some neat arrangement similar to that which I .lnave seen on the backwheel of a heavy-type touring car may be of some advantage, viz., on the inside of the wheel an ordinary thin solid tyre about 2 ins, in section was fitted, being about 3 ins. or 4 ins, in diameter smaller than the actual diameter of the pneumatic tyre itself. The function of this tyre will be.obvions ; in the event of a puncture or part deflation this ,small solid tyre would conic into play and thus take the load off the rim of the wheel.
This question undoubtedly requires further considerationif the use of pneumatic tyres is to be extended. I think in nine cases out of ten the solution of the problem would be found in fitting thin pneumatic tyres which would, in the event of one .tyre puncturing, enable the driver to run home on the non-punctured tyre.—Yours faithfully, •