Abstract: A hopper-feeder system for feeding stored powders at a uniform, controllable and predetermined rate. A spiral convoluted stirring agitator in close proximity and conforming to the hopper wall is rotated in a direction tending to lift and dilate the powder, counteracting its tendency to bridge and to undergo intermittent or non-uniform changes in density and rate of discharge. The head load upon the feeder as well as the material damping effect on the feeder are controlled by a column cutter on the agitator that undercuts the column of powder extending through the hopper opening.

Abstract: A sail system in which the sail is reefed or furled by dropping and folding it progressively into a cover extending along the foot. The cover has starboard and port cover sides extending upwardly from the foot and joining cover lifters which are in turn attached to the sail. The cover sides have closure means along their upper edges for fastening them together after the sail and fly have been fully furled therewithin. Lazy jacks extend along each side of the sail and downwardly to the foot. One or more reef lines may each extend from the foot upwards through a cover side, through a reef cringle on the sail, and downwardly to a pulley attached at the clew.

Abstract: Apparatus and method for testing the internal friction and yield strength properties of bulk solids, for use in the design of material handling equipment. A sample of the solids is confined under controlled pressure in a test cell having an annular wall converging from one end of larger cross section downwardly toward a second end of smaller cross section. The pressure at the one end is varied until the ratio of the two pressures becomes constant. The two resulting pressures are then used together with the separately measured bulk density of the solids and the angle of friction thereof with the wall of the test cell to compute the effective angle of internal friction. By a further step including removal of the pressure applying means at the other end the unconfined yield strength may be determined.