XXXIV. NORMAN SELFE. 



motion. In the now obsolete system of atmospheric railways, 

 there was a direct transmission of power to the car, which was 

 effected by exhausting the main in front of the travelling piston 

 on the car, but such a direct and continuous transmission of power 

 from the main to the travelling motor, has not however yet been 

 accomplished by means of compressed air. 



As a set off to this specially advantageous feature of power 

 transmission by electricity, that medium is at a great disadvantage 

 when power has to be stored on an automotor, and the time lost 

 in charging is compared. It would appear that where secondary 

 batteries would take, say six hours to charge from their electric 

 generator, a given number of foot pounds of energy, compressed 

 air reservoirs would only require two minutes for an equivalent 

 transference. To meet this difficulty, some electric cars working 

 with storage batteries remove the whole run-down battery, and 

 replace it with another set ready charged after every exhaustion. 

 This is manifestly a complicated proceeding as compared with the 

 instantaneous connection of an air main coupling. With coal as 

 cheap as it is in Sydney, and the greater relative cost of labour in 

 its effect on the installation and maintenance of an electrical system 

 there appears to be very solid grounds to justify the pneumatic 

 system being tested in New South Wales. It must be remembered 

 that cars carrying their own charge of power can run on the 

 ordinary street as well as on a railway, and the use of such auto- 

 motors is rapidly on the increase in Europe. The cost of running 

 per car mile on our electric tramways has noi- yet been published, 

 but it is to be hoped that we may have a paper on this interesting 

 subject during the current session. 



The other recent development to be note ? in connection with 

 compressed air, is in its application to hand hammers, and small 

 rotary machines to be applied by hand, numbers of which are now 

 on the market catalogued under the general term of pneumatic 

 tools. So rapidly have these tools come int use, and increased in 

 number, value, and importance, that the Institution of Mechanical 

 Engineers, England, recently devoted two whole meetings to their 



