CENTRIFUGAL THROWERS. 223 



split very sleDder. 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 cheai>, 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"'™ 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. Brushes 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., I^os.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. XXVII : 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 j but usually the most 

 satisfactory and convenient method is to supply the liquid within the 



