78 REPORT — 1902. 



the tension of the wire before it is wound. The reels run loose on 

 the same shaft that carries the strain-pulleys, but there is an arrange- 

 ment by which they are pressed automatically against the strain-pulleys to 

 increase their turning moment by friction against the outer rim of the 

 pulley, or against the lixed frame of the apparatus to reduce the moment. 

 By this means an adjustment of the tension is obtained, and the risk of 

 the reel being crushed by the tension of the many turns of the wire is 

 avoided. 



II. Steam-engine. — This was obtained from the Reading (U.S.) Road 

 Car Company. It has four single-acting cylinders of 2^-inch bore and 

 4-inch stroke. It weighs about 60 lb. and is nominally of 6 H.P. The 

 cost was 25?. 



The choice lay between a steam-engine and a petrol motor. The 

 steam-engine was chosen for the following reason. It is not desirable to 

 draw in a kite wire, when the wire is near the breaking-point, at a uniform 

 speed, because the speed of winding in is equivalent to an increase of the 

 wind velocity, and greatly adds to the strain. Advantage should be taken 

 of the intervals between the gusts to get in the wire, and this a steam- 

 engine without a dead point does automatically. Winding in a kite 

 during a gale on June 14 the engine acted perfectly, running fast when- 

 ever the tension of the wire slackened, and slowing down or even stopping 

 entirely when the tension was increased by a gust. Of course the precise 

 tension at which the engine stops is adjustable within wide limits by 

 adjusting the steam pressure in the boiler. 



The boiler was obtained from the Britannia Company, Colchester, at 

 a cost of 25Z. It is fired by ordinary lamp oil (paraffin), of which it uses 

 about a gallon an hour. 



III. The kites. — These are described in Symons' ' Meteorological Maga- 

 zine' for April, where also the reasons for not using the Blue Hill kite 

 are stated. 



Of these there are five ready for use and the materials for making six 

 or eight more. There are also two kites designed by, and purchased of, 

 Mr. F. S. Cody. 



Both kinds, so far as my present experience goes, seem entirely satis- 

 factory. Mr. Cody's kite flies at a rather better angle, but does not seem 

 to be quite as steady as the other. Indeed, the angle of the Cody kite 

 when made of silk and light bamboos is remarkably good. 



IV. The luire. — This is of the usual kind, but I have been supplied 

 with eight miles in one piece by Messrs. Brunton and Son, Mussel- 

 burgh, N.B. 



V. In addition to the well-known Richard instruments which have 

 been ordered, it seemed desirable to obtain, if possible, something cheaper, 

 since the risk of losing the instruments is not small. I am experimenting 

 with a cheaper form. I also hope to obtain correct determinations of the 

 maximum height and the temperature at that height in the following 

 manner. If a glass tube of uniform bore, sealed at the top, but with the 

 other end under water or quicksilver, were sent up with a kite, it would, 

 assuming constant temperature, give the maximum height, for the air in 

 the tube, under the decreased pressure, would expand and bubble out, and 

 on the descent water would rise in the tube, and the height of the water 

 or quicksilver would give the minimum pressure, and hence the maximum 

 height. This is assuming constant temperature. But if an exactly similar 

 tube were also used containing saturated vapour of alcohol, two equations 



