Janu- 



ary 



1915] 



NATURE 



507 



provided by laboratories in America. Prof. Zahm 

 is the Recorder of the Langley Laboratory of the 

 Smithsonian Institution, whilst Lieut. Hunsaker is 

 connected with the School of Technologfy, Boston. 

 Report No. 2273 is a critical study by Prof. Zahm 

 of European apparatus and methods, but the de- 

 tailed application of the criticism is still unknown 



made for him by the Cambridg"e Scientific Instru- 

 ment Co. It is probable that the installation is 

 now in working order in the Massachusetts Insti- 

 tute of Technolog-y. 



In his report Prof. Zahm g-ives brief descriptions 

 of the wind tunnels in Paris, Gottingen, and 

 London, and some of the illustrations in the report 





•V^- 



Fig. I. — Longitudinal section of the large wind tunnel, Eiffel .Aerodynamical Laboratory. 



as the re-opening of the Langley Laboratory 

 cannot yet be said to be effective. 



The present position appears to be that a scheme 

 of work has been submitted to an advisory' board 

 which advocates the provision of a wind tunnel 

 and of facilities for large-scale experiments, and it 

 appears to be intended that the work of the Lang- 



FiG. 2. — Gottingen Aerodynamical Laboratory. 



ley Laboratory should be practically unlimited in 

 its scope. 



Lieut. Hunsaker is not directly represented in 

 this report, but it is known that immediately on his 

 return to America he proceeded to erect a four-foot 

 wind tunnel similar to that at the National Physi- 

 cal Laboratory, the aerodynamic balance being 



NO. 2358, VOL. 94] 



are reproduced in Figs. 1,2, and 3. In M. Eiflfel's 

 apparatus the air current traverses the centre of a 

 large room, and one of its advantages is the 

 facility with which models can be moved into and 

 out of the air current. It is further claimed by 

 M. Eiffel that the absence of walls is an advan- 

 tage in removing some constraint usual in wind 

 tunnels. 



In the Gottingen installation. Fig's. 2 and 3, air 



I lllf ><•« 



Fir.. 3. — Fraadtl's honeycomb in wina-tunnel. 



is circulated horizontally through a tunnel contain- 

 ing four right-angle bends, and numerous guide- 

 blades are necessary in order to produce a good 

 distribution of velocity in the working section. 

 Fig. 3 gives some indication of the amount of 

 labour involved in the production of a satisfactory 

 result, and for this reason the writer was informed 

 by Prof. Prandtl that the design would not be fol- 

 lowed in a new wind tunnel under consideration. 



