The Sand Blast. 637 



The apparatus complete is the gun with the sand cylinder 

 passing through it, the socket and barrel fitted to it. 



The sand used is from Long Island beaches at North- 

 port. It is first dried and then placed quite warm in a 

 small box ; this is elevated about seven feet above the floor, 

 and outside the blast room. The bottom of the box is per- 

 forated with about a half-inch hole through which passes a 

 tin tube about the same diameter, and terminating with an 

 open extremity over a small funnel, to which is connected 

 the rubber tubing which conveys the sand through the par- 

 tition of the blast room to the sand cylinder in the gun. 



The blast is in a room by itself, open by door externally 

 and by ventilator overhead to carry off the steam and facil- 

 itate the cleaning up of the sand. Upon a wooden plat- 

 form is laid a pair of parallel iron tubes acting as tram 

 ways for a set of wheels,carrying a movable table or bed, upon 

 which is placed the slab to be blasted. This bed is con- 

 nected, by a mechanical arrangement of cog wheels, with 

 the driving machinery of the blast, so that it moves the slab 

 forward leno;thwise while beino; blasted. 



Directly over this movable bed is placed the blast gun. 

 The steam is supplied from the main boiler through steam 

 hose, which is held over the gun by a pair of rollers moving 

 backward and forward by an ingenious contrivance, and 

 which carry the gun transversely across the face of the slab, 

 while the slab is moving lengthwise beneath. The gun 

 itself is a hollow cylinder, admitting the steam on its side, 

 and when the sand tube is inserted, it becomes a double 

 cylinder. WJien the slab is placed upon the table, an iron 

 plate, cut out to leave an open shield about eight by ten 



