[Illustration: Fig. 27.--Group of aeroplanes used in experimental research. Although shown the same size in the drawing, aeroplane _a_ was 16 inches wide, and _b_ and _c_, 12 inches wide.] [Illustration: Fig. 28.--An 8-inch aeroplane which did very well. This aeroplane gave decided lifting effect when the bottom side was placed dead level, as shown at _a_.] When the aeroplane _a_ (Fig. 28) was placed in a horizontal position, and the apparatus carefully balanced, it showed at a wind velocity of 40 miles an hour, a lift of 1·56 lbs., and a drift of 0·08 lb.; at an angle of 1 in 20, a lift of 3·62 lbs. and a drift of 0·21 lb.; at an angle of 1 in 16, a lift of 4·09 lbs. with a drift of 0·26 lb.; at an angle of 1 in 14, a lift of 4·5 lbs. and a drift of 0·33 lb.; at an angle of 1 in 12, a lift of 5 lbs. and a drift of 0·43 lb.; at an angle of 1 in 10, a lift of 5·75 lbs. and a drift of 0·60 lb.; at an angle of 1 in 8, a lift of 6·75 lbs. and a drift of 0·86 lb. The blast was then increased to a velocity of 47·33 miles an hour, when it was found that the lift at an angle of 1 in 16 was 5 lbs. and the drift 0·33 lb. It will be observed that this aeroplane was only 8 inches wide, while the others were 12 inches or more. They were all rather more than 3 feet long, but the width of the blast to which they were subjected was exactly 3 feet, and they were placed as near to the end of the trunk as possible. [Illustration: Fig. 29.--Resistance due to placing objects in close proximity to each other.] The next experiments were made with the view of ascertaining what effect would be produced when objects were placed near to each other (see Fig. 29). Two bars of wood 2 inches thick, and shaped as shown in the drawing, were placed on the machine and subjected to a blast of 41 miles per hour; the drift at various distances from center to center was as follows:-- 24 inches centers, drift 6 ozs. 22 „ „ „ 6 „ 20 „ „ „ 6 „ 18 „ „ „ 6-1/8 „ 16 „ „ „ 6-1/8 „ 14 „ „ „ 6-1/4 „ 12 „ „ „ 6-1/2 „ 10 „ „ „ 7 „ 8 „ „ „ 7-3/4 „ 6 „ „ „ 8-1/2 „ 4 „ „ „ 9-1/4 „ It will be seen by this that the various members constituting the frame of a flying machine should not be placed in close proximity to each other.