6o 



NATURE 



[July 13, ign 



or four Indian races : the Aymara and Quichua in the 

 central and southern highlands; the Huancas in the 

 north; the Yungas or < hinchas along the oust, besides 

 several still unclassified tribes in the north-eastern and 

 northern territories. Krom recent accessions of material 

 d by the American museum, we are now able to 

 differentiate the Aymara, representing a dolicocephalic 

 from the middle coast people, who are brachy- 

 cephalic. Further information has now been collected by 

 Dr. Ales Hrdlicka, curator of physical anthropology in 

 the United .Slates National Museum, who has recently 

 made a hasty tuur through the coastal region and a more 

 careful examination of two important sites, Pachacamac 

 and Chan-chan or Gran Chimu. The results of his 

 investigations are published in vol. lvi., No. 16, of the 

 Smithsonian Miscellaneous Collections. 



It now appears to be certain that the whole, or the 

 1 part, of the Peruvian coast was originally peopled 

 by a race of a single type, brachycephalic Indians of 

 moderate stature. The remains of the earliest people are 

 found in the huacas and some cemeteries associated with 

 pottery of simple but interesting form-.. Metal is scarce, 

 and when found is gold. These people were followed by 

 otliers of the same fundamental type, but of different 

 habits, as is shown by the fact that their skulls have 

 been subjected to occipital flattening and fronto-occipital 

 deformations. In their graves are found copper and brass, 

 with a little gold and some simple pottery. Upon this 

 brachycephalic people a dolichocephalic race, probably 

 from the north, intruded, and were the makers of the 

 nore highly ornamented pottery, some specimens of which 

 are illustrated in this memoir. 



The material collected by Dr. Hrdlicka contributes 

 some other interesting facts. No case of rachitis was 

 observed, and in only one vertebra was there indica- 

 tions of tuberculosis; but the evidence is not quite con- 

 clusive, and the age of the grave is uncertain. The 

 specimens indicating syphilis were recent. Fractures were 

 rare, the setting defective, and there were no indications of 

 surgical skill. The evidence for trephining is confined to 

 a single case. Finally, it is clear that the ordinary collec- 

 tions of Peruvian pottery possess no scientific value, as 

 it is usually a heterogeneous mixture of specimens of 

 different races and epochs. The work of exploration must 

 begin de novo, and the new race of archaeologists must 

 adapt those methods of scientific excavation of which the 

 work of Or. Arthur Evans in Crete and Prof. Flinders 

 Petrie in Egypt are such excellent examples. 



AERONAUTIC INVESTIGATIONS: 



T V HF. Advisory Committee for Aeronautics was appointed 

 in April, 1909. The first report of the committee was 

 prepared in April, 1910, and presented to Parliament in 

 July of that year. Ai the date of the preparation of that 

 report no very large amount of experimental work had 

 been completed : the first year's work was necessarily 

 largely devoted to an examination of the ground to be 

 covered, with a view to the determination of the questions 

 upon which experimental informal inn was most urgently 

 required, and to the design and construction of the 



hi apparatus. 



The aim of the present report is to give a general 

 account of the work of the committee during the year 



: rhi inii il papers giving the detailed results 



of the various investigations which have been carried out 

 by the experimental department, with other reports and 

 memoranda of general interest which have been laid before 

 the committee, are no longer included with this report, but 

 will be collected together in a volume to be issued 

 separately. This will be referred to as the Technical 

 Report of the Committee for the year 1910-11. 



During the past year the committee has had under con- 

 sideration a large number of questions which have arisen 

 in connection with the constructional work in progress at 

 Farnborough and at Barrow. At the National Physical 

 Laboratory, also, a considerable proportion of the experi- 

 mental work has been directed towards the solution of 



From ttie Report of the Advisory Committee for Aeronautics for die 

 Year 1010-11. [Cd. 5706.) (London: Wyman and Sons, Ltd., 1911.) 

 Price Ad. 



specific problems of airship design and the determination 

 of the necessary experimental data. In addition, research 

 oi a somewhat more general character has been carried 

 out, and some results of fundamental importance with 

 reference to the future work to be undertaken have been 

 arrived at. 



Equipment jar Experimental Work. — The principal 

 apparatus which has been installed at tie: National Physical 

 Laboratory lor the purpose of the researches in aero- 

 nautics now in progress was described in the report of the 

 committee for 1909-10. The most interesting and novel 

 addition to the equipment during the past year is a circular 

 rotating water channel, to be used for determining the 

 forces acting on plates and small models in a circular 

 stream of water. It is hoped that, with the aid of this, 

 certain data ol I unilamental importance- in connection with 

 the motion of an airship may be determined, and, in 

 general, that the forces acting on aircraft when executing 

 turning movements in the air may be investigated. In 

 addition, a special water tank has been provided for the 

 study, by visual and photographic methods, of the eddying 

 motion in the rear of plane and curved surfaces, balloon 

 bodies, &c. 



Air and Water Channels. — The laboratory has now at its 

 disposal for resistance experiments two air channels — the 

 larger air channel of 4 foot square section, specially con- 

 structed for the aeronautical work, and the circular channel 

 of 2 foot diameter, previously employed by Dr. Stanton in 

 his researches on the resistance of models in a current of 

 air — and a water channel which continues to be of much 

 value for obtaining results from which the corresponding 

 data for air can be immediately deduced. 



With these various means a large amount of experi- 

 mental work has been carried out throughout the year. 

 'Phis work has included the determination of the resistance 

 of a number of airship bodies of different forms, and the 

 measurement for these forms of the " lift " and " drift 

 at various angles to the wind ; the investigation of the 

 relative stability of different airship models, and of the 

 stabilising action of fins of different area and in different 

 positions ; the determination of the efficiency of various 

 types of rudders and lifting surfaces, plane and curved; 

 the air resistance of wires, stationary and vibrating, of 

 stays and ropes, of model gondolas, model radiators, &c. : 

 the investigation of the forces due to the wind acting on 

 models of dirigible sheds of different forms; and of the 

 forces acting under various conditions on a model of a 

 girder of the type employed in the new Paulhan aero- 

 plane. 



Resistance and Directional Stability of Airship Models. 

 — Perhaps the most interesting investigation among those 

 enumerated above is that on airship models. The investi- 

 gation has comprised a large series of observations on 

 models of different forms, carried out at intervals through- 

 out the year. The work has been directed to the deter- , 

 mination of the head resistance for motion parallel to the 

 axis, the " lift " and " drift " for motion oblique to the 

 axis, the magnitude of the moment tending to increase the 

 obliquity — called hereafter the negative righting moment — 

 when the ship is at different angles to the relative wind, 

 and the amount of fin area necessary to give a positive, in 

 place of a negative, righting moment. 



The work has been carried out in cooperation with the 

 superintendent of the Army Aircraft Factory, who provided 

 the models for the tests, the head and tail curves for 

 which were systematically varied according to a plan 

 devised by him. The object of the tests for head resist- 

 ance was to determine the amount of change in resistance 

 due to specific alterations of the curvature in head or tail, 

 and ultimately to determine the forms of minimum resist- 

 ance for a given gross lifting power and for a given net 

 lift. The experiments led to the adoption of certain curves 

 for head and tail, with a ratio of total length to maximum 

 diameter of about 6 : 1. 



The experiments on models inclined to the current deti r- 

 mined the amount of dynamic lift obtainable owing to the 

 inclination of the airship to the horizontal, as distinct from 

 that directly due to the elevating planes, and at the same 

 time the increase in head resistance owing to the obliquity. 



The complete investigation of the conditions affecting 

 the stability of path of an airship will no doubt take a 



NO. 2176, VOL. 87] 



