OSCILLATING BLOWERS OF POWDERS. 237 



of an incli diameter on top of the tube, one-fourth on the sides, and 

 three-eighths on the under side. Where the powder is of less adhesive 

 character the outlets should be reduced in size and number. These 

 lioles should be crowded close together, and a slot seems preferable to 

 a row of such holes. In any of these cases a part of the blast in pass- 

 ing should be deflected out or crowded out strongly against or into 

 the powder by some device for directing it, or for chokiug the main 

 passage to crowd the blast therefrom. Where a series of holes is used, 

 the part of the blast which is forced out through the proximal holes will 

 l)ass through the powder along the outside of the tube to beyond the 

 deflecting device or obstruction, when it will re enter through the distal 

 holes into the blast passage again and this outside portion of the blast 

 operates upon the powder to feed-in a part of it into the exeurrent tract 

 of the main passage, that can communicate to and through an exten- 

 sion tube beyond, which should preferably branch, leading beneath two 

 or more pairs of rows, for the blast may be conducted through the same 

 small pipes that are used for water in squirting-machines. The outside 

 blast in the can naturally follows the surface of the tube, and thus feeds 

 out a thin layer from along its surface without catching and carrying 

 large lumps or masses to clog its passages which lead back into the 

 tube. Also on account of the blast approaching these holes at an angle, 

 nearly a right angle, and thus entering them very obliquely, changing 

 its direction to do so, clogging is less possible, and there is a strong 

 tendency to disintegrate lumps against the distal edge of the hole. 

 Further, in case the more proximate exit-hole or holes, which the blast 

 naturally passes out through at first, should become clogged, it has the 

 alternative of several others, and by thus playing from one hole to an- 

 other and across the clogged hole to reach the open one beyond, any 

 clogging lump or mass is gradually disintegrated, reopening any one 

 of the ways which may have become clogged. 



The device for causing partial obstruction of the blast-passage may 

 be permanent, but should preferably be adjustable at will, to crowd or 

 deflect off through the powder a greater or less part of the blast ; for 

 the larger the obstructions the more of the blast is diverted and the 

 greater the amount of powder it feeds out, and vice versa. A damper, 

 gate, cock, plug, or any other shut-off device may be used. 



When the powder blast is directed through small more or less branch- 

 ing tubes their terminal spray-nozzles are removed, and side holes, up- 

 ward-curved ends of pipe or deflectors may be substituted. The blast 

 of powder from these generates in the atmosphere vortical rotations, 

 which spread, mix, and diffuse the discharged powder into a cloud 

 large enough to supply a single row, which is all that is needed in pow- 

 dering from beneath. When desired the powder jets may be expanded 

 more broadly by using very wide-mouthed eddy-chamber jets, and may 

 be divided into forked jets by:double deflectors made on the plans shown 

 in Figs. 1 and 2 of PI. XIX. 



