• Control . By Wireless: Its Cost.

The Fourth Atticle, Dealing with the Application of Wireless Telephony to the Control of Transport, Goes into the Question of the Cost of the Installation. F ROM THE previous......

Simplifying Force-pump Calculations.

T HE TWO accompanying illustrations show the two sides of a " hydrocalculator " compiled and protected by Mr. E. E. G. Nicholson, who superintends the publicity department of......