240 REPORT 



a small bellows, v, with handles, It h, one of these servingas a discharge- 

 spout, communicating, through the powder receptacle, p, to its deliv- 

 ery at s. The bellows is made mechanically tight without nails, glue, 

 or other soluble adhesives, and is very strong. After binding the 

 leather into the peripheral groove of the heads by a stout wrap of wire, 

 a marginal, flange-like projection of the metallic heads, i, and the border 

 leather above the wire are clinched down over the wire. Thus the head 

 and leather are mechanically bound together in the firmest, strongest, 

 tightest, and most durable manner. Also, as hydraulic bellows these 

 cannot be surpassed, and where used for spraying liquids, as in devices 

 to be noticed below, or where employed in wet fields or driving rains, 

 this independence of harm from moisture is an excellent characteristic. 

 The suction- valve is a soft plate of leather caged, with little play, upon 

 the inlet hole which is punched through the thin metal head. This 

 hole is covered outwardly with fine brass gauze, z, to prevent coarse 

 bodies from sucking into the valve or parts beyond, and to prevent the 

 outward air-pressure from forcing the leather plate to wrinkle or bulge 

 out too much at the inlet. Instead of the many-punctured outer cover 

 one or more slots will give similar advantages in the construction of the 

 inlet. Also, the valve plate is inwardly ca^ed by gauze or bars, prefer- 

 ably by the former. This prevents the valve-plate from moving far off 

 from the inlet, so that it will close quick and never fail to overlap the 

 inargins on all sides, and it also preserves the flatness of the flexible 

 valve-plate while allowing the outward pressure to strike its outward 

 surface in a direct manner. Thus the valve is made very simple, light, 

 and effective. The discharge may be taken from either end of the hol- 

 low cleat or handle, 7i, but the arrangement shown will generally be 

 preferred, in which the blast is discharged through the left hand, be- 

 tween the powder-can,^, and the bellows, v. Thus the weight of the 

 bellows tends to balance that of the powder-can and extension- pipe, 

 rendering the tool more easily wielded than if the weight was more 

 distant from the hand. The powder receptacle may have any suit- 

 able form, but the biconic shape here shown is efS(dent, and seems the 

 simplest to make. One end is truncate, opening by the large screw-cap 

 or plug, y. The blast passage inside extends radially from the periphery 

 to the apex, with an extension- pipe, i, beyond, terminating in the crook 

 discharging at s. The extension piece is separable at r. The internal 

 relations of the blast to the powder will be better explained by observ- 

 ing Fig. 2, which is a sectional view taken longitudinally through the 

 parts. The tube, e r, inside the can, has a slot in its side, and about 

 midway in its passage is a shut-oft' device, j. When this is set, partially 

 closing the tubular passage, only a part of the blast goes through direct, 

 and the rest is crowded out to grind away the powder exposed by the 

 slot passages. The more of the blast thus crowded out, the more of the 

 powder will be fed to and carried away by the blast. To allow this 

 feeding by erosion, one, two, or more slots or rows of holes of size and 



