NO. 3 EUROPEAN AERONAUTICAL LABORATORIES — ZAHM 5 



Aeronautics ; its engineering department is directed by Dr. T. E. 

 Stanton ; and the subdivision of this assigned to aeronautic investiga- 

 tion is in general charge of Mr. L. Bairstovv. 



The part of the National Physical Laboratory devoted exclusively 

 to aeronautics comprises the whirling-table house, the large wind- 

 tunnel house and the small wind-tunnel house with its liberal space 

 for minor apparatus. The parts available for aeronautics, but not 

 e.xclusivelv devoted thereto, are the general grounds, the large marine 

 model tank, the ample shops for wood and metal working, the store 

 rooms, the ot^ces and library, the heating and lighting system, etc. 



The zvlu)li}!i:;-tablc Iwitsc. a separate building, is a corrugated iron 

 shed some 80 feet square, having an earth floor, and at its center a 

 motor driven vertical shaft which supports a trussed horizontal arm 

 and causes it to whiil at any desired speed, its outer extremity describ- 

 ing a circle about 60 feet in diameter, and carrying in steady flight 

 anv model that has to be tested. The most important use of this 

 whirling tabel hitherto made seems to have been to ])rove what was 

 demonstrated and |)ul)lished in .\merica by myself about one decade 

 previously, viz., that a suitably designed pressure-tube anemometer is 

 competent to measure the velocity of a uniform air current accurately 

 to one per cent, or less,' and needs no calil)ration when its readings 

 are interpreted in accordance with Bernoulli's theorem. The whirling 

 arm has also been used to test model screw propellers, but is not 

 necessarv for this work, and is much less convenient for the purpose 

 than the wind-tunnel, as used by Eiffel, for example. It is therefore 

 questionable whether the Smithsonian Institution will require a 

 whirling tal)le for its aerodynamic studies. 



The large zciud-tittiiiel house, a wing of the engineering labora- 

 tory, is a concrete structure 100 feet long, 40 wide and 30 high, having 

 a wooden horizontal wind-tumiel placed ecjuidistant from the side 

 walls, and midway between floor and ceiling, and supported between 

 concrete columns reaching from floor to ceiling. 



The large tunnel is some 80 feet long and 7 feet square in cross- 

 section from its mouth to its middle : it expands considerably through 

 the rest of its length. Its larger extremity abuts against the end 

 wall of the room, while its mouth stops well short of the oppo- 

 site wall. At mid-tunnel, just aft the enlargement, is placed a low- 

 pitch wooden screw actuated by a 30-horse electric motor, and 

 designed to give a current of 60 feet a second in the fore part of the 



' The calibration made at the British laboratory is reported to be relial)le 

 to one-tenth of one per cent. 



