CENTRIFUGAL THROWERS. 
223 
split very slender. Altogether, they cannot be regarded as equal to 
the better materials mentioned above. 
Whalebone is in all its properties similar to the quills and far too 
costly for use. 
Coarse hemp from untwisted ropes is very cheap, and though much 
inferior to corn for large brushes it works pretty well in small brushes 
and will probably be employed in them to a considerable extent. 
Ordinary broom wires (l n,m diameter) arranged sparsely into a brush 
with the tips about 1 inch apart throw a very fine spray. 
This and steel wire and broom-corn are the materials which now 
seem to be preferable above the others named for use in these brushes. 
Rattan, bamboo, and splintered woods can be employed, but they 
have not yet been found very satisfactory. 
As a rule brushes having considerable velocity of rotation throw a 
spray better and farther when the bristles are not sprung. If the bris- 
tles become permanently curved from being continually sprung in one 
direction the brush may be turned end for end to reverse the bristles, 
and then when rotated in the same direction it will work better than 
ever. Brashes of some materials often need to be changed thus. 
Cylindriform brushes of suitable shape are made and sold for brush- 
ing horses and polishing fine metal work by the Stow Flexible Shaft 
Co., Nos.1505 to 1509 Pennsylvania avenue, Philadelphia, Pa , and prob- 
ably by others also. But such brushes made by the usual process of 
drawing tufts of the fibers or bristles into holes in a hollow core or hub, 
which is afterward plugged, are very expensive and a still worse feat- 
ure is that they cannot be made with a small core. 
Small, even brushes, with symmetrical form, are made best and most 
economically, as in Fig. '2 of PI. XXVI I : In a cylindrical solid core turn 
out deep cir cular grooves separated by narrow rings of wood. The 
fiber is looped under a wire, whichis wrapped tightly in each groove, 
and drawn through a saw-cut across to the next one, &c. The brushes 
are thus made in the simplest and quickest manner, and the price is a 
small fraction of what the old process brushes cost. 
Soft brushes for cleaning glasses, pitchers, &c, are already manu- 
factured on the similar plan of drawing bristles into spiral grooves. 
But by this method the ends of the brush cannot be made square. 
The bristles of the brushes should be very sparse. If they are not 
far apart the water is lifted and thrown in masses which have adhered 
between them. Also the greater the velocity of rotation the fewer 
must the bristles be. When quite high motion is used, a very few, in- 
serted with shellacked pegs into awl-holes in a wooden cylinder will ans- 
wer. Home-made brushes are easily constructed on this plan, and it 
is an easy method where spring wire is used instead of fiber. 
The rotating brush may be fed with liquid by allowing it to drip from a 
small tube onto either the periphery or axis or side ; but usually the most 
satisfactory and convenient method is to supply the liquid within the 
