438 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



for this purpose had been found to be excellent, the deposit 

 of scale being small in quantity, and easily removed. These 

 statements met with considerable opposition. It was as- 

 serted that in many cases where it had been applied the 

 zinc had failed entirely to produce any useful effect; and a 

 number of authorities were quoted to prove that the success 

 of the zinc or " galvanic " process was at best questionable. 

 The opinion prevailed that in view of the vast differences in 

 the nature of the feed-water employed in different localities, 

 there could scai'cely be any universal panacea for the evil 

 of boiler incrustation. 



AN AUTOMATIC RELIEF-VALVE FOE STEAM FIKE-ENGINES. 



The damage caused by excessive flooding with water at 

 fires frequently exceeds that by fire, and any appliance that 

 prevents this is deserving of recognition. The Committee 

 of Science and the Arts of the Franklin Institute lately 

 awarded the Scott Legacy Premium and Medal to John E. 

 Prunty, of Baltimore, for his automatic relief-valve for steam 

 fire-engines, designed to give the pipeman full and instant 

 control of the stream, enabling the latter to shut off instantly 

 to prevent damage by water, to change nozzles, or to move 

 the hose easily. The valve is applied between the pump (or 

 hydrant) and the hose, and consists of a barrel-shaped cham- 

 ber, with an auxiliary cylindrical valve-chamber parallel to 

 this, and communicating therewith by two ports. A double 

 beat valve in this latter chamber allows, when open, the exit 

 of water from the main chamber through an eduction port. 

 To the stem of this valve is attached a lever with ring-shaped 

 termination floating freely in the main chamber. The areas 

 of this ring and of the poppet-valves are so proportioned 

 with respect to each other and the cut-off nozzle at the end 

 of the hose line, that when the nozzle is open and the current 

 unobstructed the water will pass through the main chamber 

 to and through the hose ; but any stoppage of the current 

 by means of the cut-ofl* nozzle, or from a wall falling on the 

 hose, etc., allows of the instant opening of the balanced 

 valves and the discharge of the water through the eduction 

 port, w^hich has a larger area than the nozzle. The water so 

 discharged may, if desired, be returned to the suction side 

 of the pump. Being entirely automatic at any pressure, and 



