August 12, 1909] 



NATURE 



205 



tion of questions as to iheir size and position ; (iv.) effect 

 of rudder action; (v.) effect of gusts of wind; (vi.) investi- 

 gations as to stability of models for different dispositions 

 of weight, &c. 



(12) Materials for aeroplane construction. 



(13) Consideration of dilfcrent forms of aeroplane, mono- 

 plane, biplane, &.C. 



(14) Other forms of heavlcr-than-air machines, heli- 

 copters, &c. 



III. — Propeller Experiments. 



(15) Efficiency and th^ effect on the efficiency of varia- 

 tions in blade area, pitch, and slip. 



{16) Positions relative to the machine. 



IV. — Motors. 



(17) Efficiency. 



(18) Trustworthiness and steadiness, 

 (iq) Materials of construction. 



(20) Design. 



V. — Questions Especially Relating to Airships. 



(21) Materials of construction, strength, &c. : — (i.) alloys, 

 A'ood, bamboo, &:c. ; (ii.) b.illoon fabrics; (iii.) wires, 

 cords. 



(22) Production of hydrogen. 



(23) Gas-tightness of fabrics. 



(24) Detection of leakage. 



(25) Air resistance to ships of different form ; experi- 

 ments on models : — (i.) effect of shape of ends ; (ii.) effect 

 of length ; (iii.) variation with speed ; (iv.) distribution of 

 pressure as affecting stability, strength in construction, 

 position of propellers, fins, &c. ; (v.) total resistance of 

 models rigged to represent different balloons. 



(26) Questions as to stability of airships in different 

 positions. 



(27) Stabilising and steering appliances, fins, rudders, 

 &c. ; form and position. 



(28) General design. 



(29) Navigation of airships. Mooring, &c. 



(30) Efficiency and position of propellers for airsliips. 



(31) Motors for airship work. 



VI. — Meteorology. 



(32) General information relating to variations of wind 

 velocity and phenomena connected with gusts of wind. 



(33) Relative variation in speed and direction of the 

 wind at different heights above the earth's surface. 



(34) Vertical movements in the air. 



(35) Rotarv movements in the air. 

 (3b) Electrical phenomena. 



(37) Formation of clouds, snow, hail, &c. 

 Eventually the committee decided that the following 

 researches should be undertaken at once : — 



(a) Experiments on air resistance and on air friction as 

 outlined in (i) to (7) above, and including experiments on 

 models of airships and aeroplanes, resistances of wires and 

 connecting stays, &c. 



(b) Motor tests. 



(c) Propeller experiments. 



(d) Tests for gas-tightness of materials suitable for 

 dirigibles. 



(e) Experiments on the behaviour of difTerent materials 

 with reference to the accumulation of electrostatic charge, 

 and generally as to means of protecting airships from the 

 1 MiTt of electrical discharges. 



The interim report points out that additions to the 

 existing buildings at the National Physical Laboratory 

 have been found necessary to provide space for part of the 

 experimental work, while a special building is also being 

 provided for the whirling table referred to below. The 

 equipment which is now being installed comprises the 

 following : — ■ 



(i.) A wind channel 4 feet square and about 20 feet long, 

 with a fan giving a draught of 40 feet per second, special 

 arrangements being made to obtain a uniform flow. This 

 will be employed for the determination of the air-pressure 

 components on plane and curved surfaces, for the resist- 

 ance of models of airships and aeroplanes, and for observa- 

 tions on the centre of pressure, frictional resistance, 

 stability, &c. 



NO. 2076, VOL. 81] 



(ii.) A whirling table of about 70 feet diameter. For 

 this a special building is being erected ; the table itself 

 is under construction in the laboratory. It ^ will be 

 employed for a repetition of Dines's and Langley's e.xperi- 

 mcnts', as well as for propeller tests, which are urgently 

 called for. 



(iii.) Two wind towers for experiments in the open. 

 These will enable some of the air-channel experiments to 

 be repeated on a larger scale in the natural wind, and 

 will, it is hoped, afford valuable information as to the 

 varying conditions which obtain in practice. 



(iv.) Apparatus for efliciency tests on high-speed motors 

 up to 50 horse-power. 



In .addition, certain machine tools, &c., are being pro- 

 vided for worlcshop use. 



The evidences provided by the interim report of the 

 activitv of the committee are gratifying in view of the 

 activity being displayed in other countries in practical 

 aviation. We notice that, on .'\ugust 7, M. Sommer added 

 another triumph to France in this province of aeronautics. 

 M. Sommer beat the world's record for length of time 

 in the air by flying at Chalons for 2h. 27m. 15s. The 

 record was previously that of Mr. Wilbur Wright, who, on 

 December 31 last, remained in the air at Le Mans for 

 2h. 20m. 23s. 



A 



THE M.iGNETIC OBSERV.ITORIES OF THE 

 U.S. CO.iST .IND GEODETIC SURVEY.' 

 LIBERAL addition made in 1899 to the funds avail- 

 able for magnetic work by the U.S. Coast and 

 Geodetic Survey enabled a great extension to be made in 

 the direction of magnetic observatories. Previously to that 

 date the only magnetographs run by the Survey were an 

 old Brooke instrument, first set up in i860 at Key West, 

 and an Adie instrument installed in 18S2 at Los Angeles, 

 and subsequently in use elsewhere. These two instruments 

 are still in use, the Brooke in modified form at Vieques, 

 the Adie at Cheltenham (fourteen miles south-east of 

 Washington, D.C.), the central station of the Survey. 

 Cheltenham also possesses a new set of Eschenhagen 

 instruments, and similar instruments were also obtained 

 for Baldwin, Sitka, and Honolulu. The curves from the 

 five observatories are tabulated at a central office, and the 

 volumes containing the earliest years' results have recently 

 appeared. The material is dealt with after a uniform 

 plan. Each volume discusses the buildings and instru- 

 ments, and enumerates the base-line and scale-value 

 changes. It is interesting to learn that the experience at 

 Cheltenham " is decidedly favourable to the old Adie type, 

 on account of its greater stability and the less frequent 

 adjustments required." Another instrumental point of 

 interest relates to the temperature coefficients of the hori- 

 zontal force instruments. That of the Adie instrument 

 appears exceptionally large for an instrument of its type, 

 but it is less than half the average value for the four 

 Eschenhagen instruments, and only one of the latter is 

 worse than the Brooke in this respect. When a rise of 

 1° C. in temperature produces the same effect in the trace 

 as a fall of 177 in the force — as seems to be the case at 

 Honolulu — satisfactory elimination of temperature effects 

 must be troublesome. If the cause lies in the quartz-fibre 

 suspension, a substitute should be sought for. 



The greater part of each volume is devoted to the hourly 

 readings from the curves. Declination and horizontal 

 intensity results are given for all the stations, but vertical 

 intensity results only for Cheltenham. Mean hourly values 

 are deduced for each month, first from all the days, and, 

 secondly, from the ten least disturbed days. The latter 

 form tiie basis of the regular diurnal inequalities given 

 for each month. Inequalities are calculated for the 

 northerly and easterly components as well as for declina- 

 tion ani horizontal intensity, and at Cheltenham for dip 

 as well as for vertical intensity. L'ndcr the heading 

 " Daily Range of Declination " we have tables of values 



1 Results of Observations made at the Toast and Genrtetic .Survey Mag- 

 netic Observatofies, Cheltenham, Maryland. 1901-4 pp. 206 ; Baldwin, 

 Kansas, iqoi-4. pp. 138 ; Sitka. Alaska, Tgo2-4, pp. 129 ; near Honolulu, 

 Hawaii, 1902-4, rp- 530: and Viegnes, Porto Rico. 1903-^, pp. 70. By 

 Daniel L.'Hazard, Coinputer. Division of Terrestrial Magnetism. (Wash- 

 ington : Government Printing Office, »gog.) 



