2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 93 



was approved by the experimental committee and was constructed 

 by John Browning, an optician and member of the Society. It was 

 set up at Messrs. Penn's Marine Engineering Works at Greenwich, 

 where the world's first wind tunnel experiments took place. 



The tunnel was a wooden trunk i8 inches square and lO feet long. 

 Through it was directed the blast from a fan, driven by a steam en- 

 gine. The wind velocity was measured with a water gauge, various 

 speeds up to 40 miles per hour being used. The wind was not steady, 

 considerable fluctuations making the observations difficult. The di- 

 rection of the wind was tested with a vane and said to be fairly 

 straight, although there is no mention of a wind straightener of any 

 kind. 



The balance was exhibited and explained to the Society by Mr. 

 Wenham. It consisted of a vertical steel spindle, supported on a 

 hardened steel center. Through an eye at the upper end of the spindle 

 passed a horizontal weighing beam, supported by a cross pin axle. The 

 long end of the beam carried the testing planes which could be set at 

 various angles of incidence while they were always kept at right angles 

 across the current. The short end carried a sliding counterweight so 

 as to balance the testing plane. The drag was measured by a spring 

 steelyard connected to a lever from the vertical spindle, close to the 

 base of the machine. The lift was read off by a vertical spring steel- 

 yard. 



The balance with the testing planes was placed in front of the 

 tunnel at a distance of 2 feet, a wooden shield covering the balance 

 and leaving only the planes exposed to the wind. Lift and drag were 

 measured simultaneously, two persons making the observations. Only 

 plane surfaces were tested, the largest being 18 inches across, the 

 same width as the tunnel. They were placed at various angles from 

 15° to 60°; tests on smaller angles were found to be very desirable 

 but could not be achieved with the instrument at hand. 



In spite of the crudeness of the tunnel and the shortness of the time 

 allotted for experiments, the results were the most satisfactory of the 

 kind obtained to that time. The experiments were very encouraging 

 to aviation enthusiasts, as they proved that the lift at small angles 

 exceeds the drag to a much greater extent than had previously been 

 suspected. The desirability of a large aspect ratio and the location of 

 the center of pressure near the leading edge were also demonstrated. 

 The test data were published in tabular form in the Report of the 

 Aeronautical Society. These tables were widely used and were also 

 made the basis for actual construction, particularly by Thomas Moy 



