October 21, iS^y] 



NATURE 



599 



extracted ami weighed from equal quantities of hair of the 

 four several colours, because there is room for doubt as to the 

 medium tints of those colours, and because those mediums may 

 not be precisely the same in America as here. It seemed better 

 to work the problem backwards, in the way to be easily under- 

 )od from the following example. The [bay— bay] unions, 

 cording to Table I., produce lo per cent, of chestnut offspring, 

 I per cent, of bay, 6 per cent, of brown, and 3 per cent, of 

 lack. Therefore the quantity of red contained in each hundred 

 llspring of [bay — bay] parents should be reckoned at 

 10 X 08 + 81 X 07 + 6 X 0-4 + 3 X o'l = 67'4 units. 

 Since this is the amount of red contributed by the two bay 

 l^arents, the contribution from either bay parent singly will be 

 i>\\\y half as much, or 337. 



Similarly the contribution of red from a single chestnut parent 

 will be found to be 40*0 ; of a brown, 25*3 ; and of a black, 

 iO"4. Consequently the quantity of red in each hundred off- 

 spring of [bay and brown] unions will, according to the theory, 

 be reckoned at 



337 + 25-3 = 59 units. 



This number has been entered in its proper place in Table 



III. as the 'calculated" value, and may there be compared 



with the " observed " value obtained from the reciprocal unions 



of [Dam, bay — Sire, brown], and of [Dain, brown — Sire, bay]. 



\ow, the former of these is seen in Table I. to have produced 



I per cent, of chestnut, 79 per cent, of bay, 14 per cent, of 



rown, and 6 per cent, of black, yielding by the method just 



described, 62'3 units of red ; by a similar treatment the latter of 



these unions, namely [Dam, brown — Sire, bay] ^vill be found to 



yield 59 2 units. The mean of 62-3 and 59^2 being 6075, that 



!- 61 when reckoned to the nearest integer, is also entered in a 



cparate column in Table III. 



Table III. — Amount of Red in Offspring, observed and 

 calculated. 



The general result of the comparisons is that calculation 

 agrees with observation as closely as the rudeness of the statistics 

 could lead one to expect. The average error between each of 

 the six calculations and the corresponding means of each of the 

 six pairs of reciprocal observations is about 5 per cent. , while the 

 greatest error barely exceeds 10 per cent. I therefore consider 

 these results to corroliorate that part of my theory of inheritance 

 which they were intended to test. 



Permit me to take this opportunity of removing a possible 

 misapprehension respecting the scope of my theory. That theory 

 is intended to apply only to the offspring of parents who, being 

 of the same variety, differ in having a greater or less amount of 

 such characteristics as any individual of that variety may 

 normally possess. It does not relate to the offspring of parents 

 of different varieties; in short, it has nothing to do with 

 hybridism, for in that case the offspring of two diverse parents 

 do not necessarily a.ssume an intermediate form. 



I am further desirous of drawing attention to an absurd error 

 in my recent memoir quoted above, through the accidental 

 transposition by me of the words Dam and Sire in the side 

 columns of the Table II. of that memoir (which Table was con- 

 structed out of the Table I. that preceded it). The result was 

 that the potency of the Dam to that of the Sire in transmitting 

 colour was stated to have come out as 6 to 5, whereas the 

 fact is the exact converse, namely, as 5 to 6. I ought to add 

 that this strange blunder, which was detected and obligingly 

 pointed out to me by two separate correspondents, had no 

 effect upon the general conclusions of the memoir, because the 

 ratio of 6 to 5 was treated as an insignificant disproportion, 

 and the two sexes were dealt with on equal terms. 



Francis Galton. 



AERONAUTICAL ASCENTS FOR MEASURING 



THE ELECTRICAL FIELD OF THE AIR. 

 QN September 11, M. Lecadet, astronomer of the Lyons 

 Observatory, made his fifth aeronautical ascent for testing 

 the electricity of the air at high altitudes. This system of 

 observation was invented by Dr. Exner, a member of the 

 Vienna Academy of Sciences, who sent into the atmosphere a 

 balloon directed by Lechner, on June 6, 1885. The balloon 

 reached only an altitude of 600 metres, and the results of the 

 reading, taken by an inexperienced observer, were of no value. 



On September 27, 1892, M. Andree, director of the Lyons 

 Observatory, determined to ascend himself, with M. Lecadet as 

 his assistant. The ascent ended in a total wreck. 



In the following year M. Lecadet made two ascents at Meudon 

 with the Government balloon, after having procured permission 

 from the War Office. In the first trip (August 1893) the 

 balloon was conducted by Captains Paul Renard and Julian, and 

 ascended only to a very moderate altitude. The second experi- 

 ment took place on August 9, and only one officer, Captain 

 Hugot, was sent up with M. Lecadet. The experiments showed 

 that the electrical field of the air gradually diminished, though 

 the measures were executed with the cumbersome instrument 

 ! designed by Dr. Exner. 



In the following month, in September 1893, two ascents were 

 made from Tempelhof, with the balloons of the Prussian Govern- 

 ment, by Dr. Bornstein, a member of the Berlin Society for 

 I Aerial Navigation. The results were about the same as those 



observed by Lecadet. 

 i After carrying out these experiments, M. Lecadet devised 

 a new instrument. The readings are taken with an Exner 

 electrometer, but instead of being placed in equilibrium with 

 the electricity of the air by two jets of water at a vertical distance 

 of five metres from each other, the effect is obtained ■ by two 

 cylinders of paper impregnated with nitrate of lead, which, 

 once being lighted, are burning without flame. They are placed 

 each to the extremity of one single wire, whose length can be 

 varied at will. The apparatus weighs 3 or 4 kilogs., instead 

 of at least 50. Many experiments made at Lyons Observatory 

 proved that there was no danger of ignition of the gas issuing 

 from the balloon, but the Minister of War declined the proposal 

 of authorising ascents from its balloon arsenal. 



The first experiment with the new system was tried at Lyons 

 a few months ago with M. Boulade, an able local aeronaut. 

 The experiments were conducted with great care and success 

 up to 1000 metres, and the electric field of the air was again 

 found to gradually decrease. 



As Lyons is in close vicinity with the Alpine district, it was 

 considered unsafe to try an ascent at a great altitude under 

 these circumstances. M. Lecadet therefore went to Paris, and 

 secured the assistance of M. Besan9on, a member of the inter- 

 national committee for the Balions Sondes. The balloon had 

 a capacity of 17CX) cubic metres ; it was a new one, in China silk. 

 There was no cloud in the sky, and only some vapour near 

 the earth's surface. The two aeronauts reached an altitude 

 of 4200 metres. The wind was rather strong, as in five hours 

 they ran about 220 miles in a W.S.W. direction. They landed 

 at Aubigne (Marne et Loire) in a regular gale, but escaped 

 unhurt, owing to the use of a special grapnel and tearing-rope 

 invented by M. Besanfon. 



The readings taken were very numerous— about 300 — and the 

 results are a continuous decrease of the electric field from the 

 level of the ground. Through the courtesy of M. Lecadet, we 

 are enabled to give the summary of results, which will be laid 

 before the Academy of Sciences by M. Mascart when all the 

 calculations have been completed, which will require some time. 



Altitude 



Close to the earth 

 1000 metres 

 4200 ,, 



120 volts 

 39 » 



NO. 1460, VOL. 56] 



The results show that at about 6000 metres the — will be 



A/ 

 almost o. Then the balloon will have reached the surface of 

 electrical equilibrium. 



If the electrical tension at this altitude is supposed to be o, 



the potential of the earth 2 - = - 160,000 (about). The 



eminent director of the French Meteorological Service has ex- 

 pressed his satisfaction at the results obtained, and has suggested 



