232 EEPORT 4, UMTED STATES ENTOMOLOGICAL COMMISSION. 



an upward direction. The method of feeding the powder to the blast 

 looks as thougli it cannot prove satisfactory. 



" Some suggestions made hj the inventor as to the use of his machine 

 for applying vapor and fine spray of liquid poison will be found men- 

 tioned further on."* 



EoTARY BLOWEKS OF LIQUID. — In endeavoring to produce rotary 

 fans for blowing poison fluids the most difficult part of the problem 

 pertains to feeding them to the blast. Since a blower will throw out 

 any amount of fluid that is allowed to flow in, and this as fast as it 

 enters, the quantity admitted must be limited to only so much as will 

 make a spray of the quality and size desired. Also, the less fluid the 

 finer and farther will it be blown, and if the supply is too great it will 

 be dipped out or splashed in great masses or very large drops, which 

 are not thrown far but wasted. To regulate or control this three meth- 

 ods prove applicable. The first is by means of a rotary brush, as al- 

 ready set forth in speaking of brush sprays. The second consists in 

 reducing the orifice of the feed-pipe from the reservoir to such size 

 that it will conduct just so much as is desired and no more j that is, by 

 means of a shut-off* device or a small drip, by which the water enters 

 the drum above so as to fall upon the revolving fans, or at some other 

 point to accumulate in the bottom of the drum and be dipped up by 

 them. The third principle is that employed in automatic inkstands, 

 but applied on a larger scale. The reservoir is air-tight, closed by a 

 can screw or plug. Its outlet is near its base, and extends through a 

 tube leading into the bottom of the drum, where the fluid can flow in 

 only just deep enough to shut off the entering of air into that end of 

 the tube, while air will be admitted and the fluid pass out only so fast 

 as the latter is lifted out by the fans. 



To prevent each fan from scooping up too much, also to divide the 

 water mechanically and ventilate it thoroughly, the dipping ends should 

 be provided with long comb like teeth. The best results are secured 

 by bending each alternate tooth forward or backward at its base, thus, 

 to make a double row, and then bend forwari nearly at a right angle 

 the distal half of each of ail the teeth. This arrangement of the teeth 

 is shown in Plate XXYII, Fig. 6, i, and is explained below. 



The fans, by their rotation, give the fluid a tangential momentum, 

 but the air current is a very important element, as I have shown by 

 using toothed reels without fans on them. They are only equivalent to 

 rotary brushes, which are here surpassed by introducing the superadded 

 blowing power of the fans. 



The outlet from the drum should be large. In case it be low down 

 ux^on the side, many drops will fall from or near it and the water may 



* To aToid much repetition of reference to Bulletin 3, U. S. Entomoloo-ical Com- 

 mission, the first edition of this work. Prof. Barnard's credit-references to said 

 Bulletin are omitted, so that all quoted matter, unless otherwise credited, is taken 

 tiierefrom.— C. V. R. 



