620 TRANSACTIONS OF SECTION G. 
training on a broad basis, and to secure to every future engineer worthy of the 
name the advantage of learning his professional work in both its aspects. It 
seeks, in short, to take advantage of that reflex action between science and its 
applications in which lies the greatest stimulus to progress. Its adoption will 
utilise for the young engineer, and therefore for the engineering industry as a 
whole, the facilities for training now so widely afforded throughout the country. 
If the institutions, schools, and colleges where engineering training is offered are 
but rightly developed and co-ordinated, the engineers of Great Britain need have 
no fear as to holding their own against the trained engineers of other countries 
It is for the employers to make use of these institutions, and to show that 
sympathetic interest in their efficiency which is essential to their full success. 
The following Paper was then read :— 
The Present Condition of Gas and Petrol Engines.\ 
By Ducarp Crier, VW Inst.C.£. 
FRIDAY, AUGUST 2. 
The following Paper was read :— 
On the Gases exhausted from a Petrol Motor.? 
By B. Hopxinson, M.A. 
Joint Discussion with Section B on Explosion Temperatures.3 
MONDAY, AUGUST 5. 
The following Papers were read :— 
1. Pupin’s Compensated Cable for Telephone Transmission.* 
By Sir W. H. Preece, K.C.B, RS. 
2. Tuning in Wireless Telegraphy. By Sir Outver Lopas, F.R.S. 
The principles of tuning were clearly explained by Mr. Duddell in his evening 
lecture to the Association last Friday, and I shall assume them known; but it 
is not to be supposed that the application of these principles requires the arc. 
Sufficient tuning for all practical purposes can be obtained by using the right kind 
of spark. It is possible to require too long a train of waves, in which case the 
latter half of the train will undo what the former half has begun, in analogy with 
beats. Thirty or forty swings can be easily got by a spark, and that is enough for 
practical requirements. 
Effect of the Earth. 
But attention to the spark alone is not sufficient; it is necessary to eliminate 
the influence of the earth. 
For the snappy or non-tuned emission, such as was employed by Mr. Marconi 
for great distances, it is convenient to use an elevated wire on the one hand, and 
the earth on the other; but for a tuned station this is not appropriate. 
1 Published in Hectrician, August 9. ? Published in Hngineering, August 9. 
8 Reported in Engineering, August 9. ‘ Published in Hlectrician, August 9. 
