showing guarded disc capable of being lowered further than shown, which acts as a collector for the detached abrasive from the revolving disc and the fine wood dust removed from the article being surfaced.

Two pipes attached at the top of the collector "A" form a junction into one branch pipe 31⁄2 inches in diameter. The pipe on each arm is swiveled, the whole offering no obstacle in the operation of the machine. An air velocity of 4005 lineal feet per minute maintained in the branch pipe successfully removes the dust from the work.

No. 56-Belt sanderequipped with extension pipe for exhaust as a means to catch and remove abrasive and wood dust disengaged at the point of origin. This pipe being telescopic can be adjusted to a point where the dust is given off, namely where the work is performed. High air veloci ties are necessary, above 4 inches static suction, suc cessfully to catch all the dust disengaged. 5650 lineal feet per minute, cor responding to 4 inches of static suction, is maintained in the above instal

No. 65

Horizontal sand drums to which are attached at side hoods equal to the sand drums' length. These hoods, which extend to the top of the drums, fail to catch all the dust thrown off from the drums when used, because the air velocity within the pipes connected to the hoods is low, below 2000 lineal feet per minute. equivalent to 11⁄2-inch static suction. Surfacing is done on the top of each drum, the fine dust being drawn into the hood. The device is not very effective because the dust is held in the sand paper and, as the wheel turns, some is thrown into the operator's face. ib