428 



A' A TURE 



[September 3, 1908 



.tribe, and there have been times when I have thought I 

 caught the rumination : — 



Sky. Three thousand ducats ? 'tis a good round sum ! 

 £as. Kor the which, as I told you, Antonio shall be bound. 



Shy. Antonio is a good man '? 



Bas. Have you heard any imputation to the contrary ? 



Shy. No ! no, no, no, no. . . . Yet his means are in supposition : 

 he hath an argosy bound to Tripolis, another to the Inoies ; I understand 

 moreover, upon the Kialto, that he hath a third in Me.\ico, a fourth foi 

 -England, and other ventures he hath squandered abroad. But ships are 

 but boards, sailors but men. There is the peril of water, winds, and 

 rocks. . . . Three thousand ducats. 



We at the Meteorological Office are very much in 

 j\ntonio's position. Our means of research are very much 

 in supposition : four observatories and more than four 

 hundred stations of one sort or another in the British 

 Isles ; an elaborate installation of wind-measuring apparatus 

 at Holyhead ; besides other ventures squandered abroad ; 

 an anemometer at Gibraltar, another at St. Helena ; a 

 .sunshine recorder at the Falkland Isles, half a dozen sets 

 of instruments in British New Guinea, and a couple of 

 hundred on the wide sea. The efforts seem so discon- 

 nected that the rumination about the ducats is not un- 

 natural. 



And you must remember that we lack an inestimable 

 advantage that belongs to a physical laboratory or a school 

 ■of mathematics, where the question of the equivalent 

 number of ducats does not arise in quite the same way. 

 The relative disadvantage that I speak of is that in an 

 office the allowance for the use of time and material in 

 practice and training disappears. All the world seems to 

 agree that time or money spent on teaching or learning 

 is well spent. In the course of twenty years' experience 

 at a physical laboratory, and in examinations not a few, 

 I have seen /||i and flj or the wave-length of sodium light 

 determined in ways that would earn very few ducats on 

 the principle of payment by results ; but, having regard 

 to the psychological effect upon the culprit or the examiner, 

 ithe question of ducats never came in. Wisely or unwisely 

 public opinion has been educated to regard the psycho- 

 logical effect as of infinite value compared with the 

 immediate result obtained. But in an office the marks that 

 an observer or computer gets for showing that he " knew 

 how to do it," when he did not succeed in doing it, do 

 not count towards a " first class," and we have to abide 

 by what we do ; we cannot rely on what we might have 

 done. Consequently our means in supposition, spread over 

 sea and land, are matters of real solicitude. In such 

 circumstances there might be reason for despondency if 

 one were dependent merely upon one's own ventures and 

 the results achieved thereby. But when one has the 

 advantage of the gradual development of investigations of 

 long standing, it is possible to maintain a show of cheer- 

 fulness. When Shylock demands his pound of flesh in the 

 form of an annual report, it is not at all uncommon to 

 find that some argosy that started on its voyage long ago 

 "hath richly come to harbour suddenly." There have 

 been quite a number of such happy arrivals within the 

 last few years. 



I will refer quite briefly to the interesting relations 

 between the yield of barley and cool summers, or the yield 

 of wheat and dry autumns, and the antecedent vieli of 

 eleven years before, which fell out of the body of statistics 

 collected in the Weekly Weather Report since 1878. The 

 accomplished statisticians of the Board of Agriculture have 

 made this work the starting-point for a general investi- 

 gation of the relation between the weather and the crops 

 which cannot fail to have important practical bearings. 



Let me take another example. For more than a full 

 ■generation meteorological work has been hampered bv the 

 want of^ a definite understanding as to the real meaning 

 in_ velocity, or force, of the various points of the scale of 

 wind-estimates laid down in 1S05 by .Admiral Beaufort for 

 use at sea, and still handed on as an oral tradition. The 

 prolonged inquiry, which goes back really to the report 

 •upon the Beckley anemograph already referred to, issued 

 quite unexpectedly in the simple result that the curve 



^ = 001053' 

 fwhere p is the force in pounds per square foot, and B 

 1he arbitrary Beaufort number) runs practically through 



NO. 2027, vor,. 78] 



nine out of the eleven points on a diagram representing 

 the empirical results of a very elaborate investigation. 

 The empirical determinations upon which it is based are 

 certainly not of the highest order of accuracy ; they rely 

 upon two separate investigations besides the statistical 

 comparison, viz., the constant of an anemometer and the 

 relation of wind-velocity to wind-pressure, but no sub- 

 sequent adjustment of these determinations is at all likely 

 to be outside the limits of an error of an estimate of wind- 

 force ; and the equation can be used, quite reasonably, as 

 a substitute for the original specification of the Beaufort 

 scale, a specification that has vanished with the passing 

 of ships of the type by which it was defined. This result, 

 combined with the equation J = 0003V", which has been 

 in use in the Office for many years, and has recently been 

 confirmed as sufficiently accurate for all practical purposes 

 by Dr. Stanton at the National Physical Laboratory and 

 Monsieur Eiffel at the Eiffel Tower, places us upon a new 

 plane with regard to the whole subject of wind-measure- 

 ment and wind-estimation. 



Results equally remarkable appear in other lines of 

 investigation. Let me take the relation of observed wind 

 velocity to barometric gradient. You may be aware that 

 in actual experience the observed direction of the wind is 

 more or less^ along the isobars, with the low pressure on 

 the left of the moving air in the northern heitiisphere ; 

 and that crowded isobars mean strong winds.' Investiga- 

 tions upon this matter go back to the earliest days of the 

 Office. 



There can be no doubt that the relation, vague as it 

 sometimes appears to be upon a weather chart, is attribu- 

 table to the effect of the earth's rotation. In order to 

 bring the observed wind velocity into numerical relation 

 with the pressure-gradient Guldberg and Mohn assumed 

 a coefficient of surface " friction," interfering with the 

 steady motion. The introduction of this new quantity, not 

 otherwise determinable, left us in doubt as to how far 

 the relation between wind and pressure distribution, 

 deducible from the assumption of steady motion, could be 

 regarded as a really effective hypothesis for meteorological 

 purposes. 



Recent investigations in the Office of the kinematics of 

 the air in travelling storms, carried out with Mr. 

 Lempfert's assistance, have shown that, so far as one can 

 speak of the velocity of wind at all — that is to say, dis- 

 regarding the transient variations of velocity of short period 

 and dealing with the average hourly velocity, the velocity 

 of the wind in all ordinary circumstances is effectively 

 steady in regard to the accelerating forces to which it is 

 subject. This view is supported by two conclusions which 

 Mr. Gold has formulated in the course of considering the 

 observations of wind velocity in the upper air, obtained in 

 recent investigations with kites. The first conclusion is 

 that the actual velocity of wind in the upper air agrees 

 with the velocity calculated from the pressure distribution 

 to a degree of accuracy which is remarkable, considering 

 the uncertainties of both measurements ; and the second 

 conclusion affords a simple, and I believe practically new, 

 explanation upon a dynamical basis of the marked differ- 

 ence between the observed winds in the central portions 

 of cyclones and anti-cvclones respectively, by showing that, 

 on the hypothesis of steady motion, the difference of sign 

 of the effective acceleration, due to curvature of path and 

 to the earth's rotation respectively, lends to quite a small 

 velocity and small gradient as the limiting values of those 

 quantities near anti-cyclonic centres. 



This conclusion is so obviously borne out by the facts 

 that we are now practically in a position to go forward 

 with the considerable simplification which results from 

 regarding the steady state of motion in which pressure 

 gradient is balanced by the effective acceleration due to the 

 rotation of the earth and the curvature of the path, as the 

 normal or ordinary state of the atmosphere. 



I cannot forbear to add one more instance of an argosy 

 which has richly come to harbour so lately as this summer. 

 You may be aware that Kelvin was of opinion that the 

 method of harmonic analysis was likely to prove a very 

 powerful engine for dealing with the complexities of 

 meteorological phenomena, as it h.ns, in fact, dealt with 

 those of tides. In this view Sir Richard Strachey and the 

 Meteorological Council concurred, and an harmonic 



