70 The Tea insects of India. 



expense. The principle cannot be pateoted, for since 1875 similar coal-oil pans, 

 virtual outgrowths of the canvas frames originally employed for the same purpose, 

 have been 'known and used ' in Colorado. This fact is sufficient in law to defeat 

 any patent right based upon any application for a patent subsequent to such Imow- 

 ledge and use. 



" The essential features in all the contrivances are in fact — (1) a platform that 

 runs on the ground, on runners or wlieels ; (2) a canopy at right angles with it ; 

 (3) a reservoir at the junction to contain the liquid. 



" Another pan .... was made by Mr. James Adams, of Abilene, Kansas. It is 

 10 feet long, 2 feet wide; back (a) 1 foot high ; front (S) about 2 inches high at 

 the inner edge ; ends {c) 2 feet high. The front is made of a board 6 inches wide, 

 leaning inward at an agle of about 45°. A cloth screen is placed on the back part' 

 which prevents the reel from knocking the locusts back over the pan. 



" The whole is made of pine, and it costs |8 or $10. The pan is painted within 

 with asphaltum paint, which renders it impervious to water or oil. The pan rests in 

 front upon runners, to which ropes are attached for drawing, and on wheels behind 

 which carry belts to turn the reel. 



" The reel revolves jnst in front of the pan, causing the locusts to hop, and then 

 knocking them into the pan. A brush of cloth is sometimes fastened to one arm 

 of the reel to brush into the pan any locusts that may be on the front-piece. Several 

 of these pans were used about Abilene, and did good work. 



" A contrivance . . . . was constructed by President John A. Anderson for use 

 on the Agricultural College farm at Manhattan, Kansas. 



" It was found to do very good service, killing the J'oung locusts in considerable 

 numbers. The oil did not evaporate so rapidly as was anticipated. One thorough 

 saturation was sufficient for fifteen or twenty minutes, when a little more could be 

 added. If the machine be hauled against (the wind, nearly all the locusts which 

 hop will touch the oiled canvas. They generally take several hops upon the canvas 

 before leaving it, thus ensuring a thorough saturation with the oil. After hopping 

 from the apron tbey can take two or three hops upon the ground, then lose all power 

 in their hind legs, stretching them straight out behind, and finally, in one or two 

 minutes after being ' oiled,' they are dead. 



" Coa^^ar.— This may be used with most of the contrivances just described for 

 the use of kerosine, and while not equal to the simple kerosine pan for speed in trap- 

 ping and destroying, is yet very useful, especially in the neighbourhood of gas works, 

 where the coal-tar can be obtained at nominal cost. It also permits the use of the 

 simplest kind of pan. Enough tar is spread over whatever receptacle may be used to 

 cover well the bottom, and when this becomes sufficiently matted with the young 

 locusts so as no longer to destroy the new-comers, another coating is added, and so on 

 until it becomes necessary to remove the whole mass, when it is shovelled from tlie 

 pan and burned, or, what is far preferable, wherever there are wet ditches it may be 

 ihrown into these, when the oil contained in it, spreading over the surface of the 

 water, destroys such locusts as may jump into or be driven into such ditches. Where 

 the tar is scarce, as a matter of economy it will pay to melt the accumulated mass in 

 iron vessels. By skimming ojf the dead locusts that rise to the surface, and thin* 

 ning the residuum with a little coal-oil, it may be used again. 



•' A simple pan extensively employed .... was known as the Robbins ' hoi^x^ev- 

 dozer,' . . . the general plan being that of the ordinary road scraper. Its simplicity 



