APRIL 23, 1903] NATURE

During the past century the Lyrids been to to have been noted i.n the stream of Leonids' on the morn• pretty close observation. The star shower seen m Amenca ings of November IS and 14, in I871 and I872, on November on the morning of April 20, r8o3-just roo years ago-seems 13, 1879, and on the morning of November 14, I888, when to have far excelled in brilliancy its Lyrid successors, though in a watch of 2!h. until daybreak, at Bristol, Mr. Denning a display witnessed, it is supposed, in r86o in the equatorial noted the appeara nce of 17 Leonids, although such strong regions of Africa is described as having rivalled in splendour recurrences of the shower are only rarely seen in the interval the November meteor-shower of r866. Shooting stars were of some thirty years between .the maximum Leonid displays. seen in unusual numbers in America on April 20, 1838, and But the comet 1861, I., of which the Lyrid shooting-stars Prof. Forshey observed a Lyrid display in Louisiana on the are supposed to be the streaming wake of pulverised night of April 18, 1841, when he counted sixty meteors in materials, is one. of those which it was pointed out by Prof. hours, which gives a mean rate of twenty-four per hour for G. Forbes in his important paper in the Observatory 1888; one observer. On the morning of April21, 1863, these meteors on the probable existence of an ultra-Neptunian planet, may were reckoned by an English observer as appearing at the presumably have been captured by such a planet, and whuld rate of forty per hour. On the night of April 18, 1876, a party thus be moving now with long periodic time in a very long of American students casually noticed that shooting stars elliptic orbit ; and this would seem to be a rather seri,ous were unusually numerous during the hours 10 to 12. Lyrid objection to the short period of 19 years assigned in Mr. meteors were also conspicuous on the night of April 20, Henry's letter to the meteor, unless it should be really true, I874· Mr. Denning has recorded important appearances of which seems hardly probable, that the meteors and the wake Lyrid meteors in I882 and 1884, especially in the latter year of dust-materials of the comet are only accidentally in ex• on the night of April 19. The same observer has also stated tremely near agreement in their radiant points, and may that the Lyrid radiant was unusually active in I893 and yet not be actually associated together with each other in I901, in the former on the nights of April 20 and 21, and in a common orbit. the latter on that of April 21. The foregoing are the most In its two last returns in I90l and 1902, the Lyrid shower important displays on record since April 20, I8o3. Periods was very distinctly observed to attain its greatest bright• of somewhat different lengths have been proposed with ness on the night of April 2 I, and as this retardation of a respect to the Lyrid showers, but the true period seems to day from its usual date of April 20 accords like the present be one which overlaps, and consists of nineteen years. similar retardation of. the January, August, October and Thus, from I803 to t86o, we have exactly three periods of December showers with the postponement of all annual nineteen years, and from 1803 to 184I, two periods of the events by one day, since February, I9oo, from same length. Again, thirty-eight years, or twice nineteen the omissiOn at the end of that month of the usual four• years, separate the showers of 1838 and I876. The nineteen• yearly leap-year day, attention should certainly, in the yea r period also connects the displays of 1863 and I882, of expectation of its fixity, be directed again to the I874 and I893, and of I882 and I90I. This nineteen-year mght of April 2 I, in the approaching Lyrid period, as well cycle is specially interesting, as it is completed at the Lyrid as to that of April I9, which the very interestingly detailed epoch of the present year, reckoning from the somewhat evidence presented in Mr. John R. Henry's letter shows important display of April I9, r884. A calculation made also to be one ·on which an unusually bright display of the by the writer indicates that the maximum in I903 is on April Lyrids may perhaps be expected. April 19, wh. 3om. G.M.T. The Lyrid radiant ought there• A. S. HERSCHEL. fore to be found active in the early part of the night of April Observatory House, Slough, April rs. 19, probably from the hours 9 to I 2. There is no prospect of Lyrids being numerous on the nights of April 20 and 21. jOHN R. HENRY. Mendel's Principles of Heredity in Mice. APPRECIATE Prof. Weldon's reluctance to defend his position in a short letter, and I look forward with peculiar UNLIKE the August P erseids, the Lyrid meteor-stream mterest to the number of Biometrika where I gather this like those of the Quadrantids, Orionids and · Geminids task will be undertaken. January, October and December, seldom exhibits an Though deferring a reply on the simple matter of tht abundant shooting-sta r display, more nearly resembling in eye-colour in the Oxford mice, Prof. Weldon finds space that respect the Leonid and Bielid meteor-systems than the to ask an " explanation " of two over-lying complexities. st;eam of August Perseids, its materials appearing to be To debate these finer points with one who doubts the Men• st1ll collected in one or more dense clusters in its orbit. Its delian nature of the phenomena taken as a whole is like brightest as well as its ordinary apparitions are also like the perturbations of Uranus with a philosopher those of the Leonids, of remarkably short duration, so 'as to who demes that the planets have orbits. Still at the risk very liable to escape observation unless splendid enough of diverting attention from the main issue, I 'will suggest t() arrest attention at some observing sta tion on the globe. how these complications may be regarded-scarcely " ex• 1 he great shower seen in America on the morning of April plained." 20, r8o3, only lasted in full splendour for two hours, from (I) The " lilac " mice illustrate that resolution and rh. to 3h. a.m.; and a rather sensational abundance of the partial disintegration, of characters commonly Lyrids on the morning of April 21, r863 , was entirely con• whe.n a compound colour is crossed with an albino. The to the night of April 20, when 1 I meteors, chiefly statistical value of the "lilacs" and their place in the colour• Lynds, were seen at Hawkhurst in 4sm., and 7 bright and system can only be determined by further breeding. The several smaller ones were observed in 3om. at Weston-super• appearance of " lilacs " or a nalogous types is what we mare, between I I h. and I2h., and in a quarter of an hour exp_ect, thoug? their absence in the offspring of hybrids x after ISh., at Hawkhurst, II shooting-star tracks were albmos constitutes a certain problem. This and other noted, the meteors falling too rapidly then in all directions genuine call for statement and analysis. to be all recorded ; the radiant point obtained from that (2) The drvers1ty of coats m the first crosses points to night's _tracks, and from a few mapped on April 19 heterogeneity among the gametes of one or both " pure " (23 Lynd paths together, some of which may perhaps really races. The nature of that heterogeneity is the question. 0 0 have other centres), was at 277! +34! , close race may breed true to colour, but the cross-bred off• to the posrtron ,which fi_rst obtained of it " near a Lyrre," spnng of the two is not necessarily uniform. The pig• by Prof. . E. C. He;nck, 1n America, 24 years ea rlier, on ment excreted by heterozygotes may, as I could easily the _mornmg of Apnl I9, I839· On the preceding night, of demonstrate, dep;nd on factors (probably determinable) Apnl 19, the hourly rate of meteors from wh. to rrh. was <;>ther than the _colours of the parents, and having an only ordinary, on the night of April 22, not a single md.ependent drstnbutwn amongst their gametes. Also, meteor was seen In an hour by either of two observers who whrle we are comprehensively assured that the coloured race watched the clear sky simultaneously from IIh. rsm. to was oure, the precise, if as yet uncontrolled, testimony of 12h. ISm. in London and at Hawkhurst for hoped-for the records that certain individuals were not, seems to have accordances. 1 Records of bright Lyrid showers are therefore of peculiar F:om a taJ>le of observations of the Leonids from 1870 t<> 1E96, rn a P1 r t1on of Mr W. F. Denning's admirable review of the whole interest, as they may not improbably represent clusters of hl5tory of " The Great Meteoric Shower of Novt:mber" · the Obser·Nr.tory meteor-dust along the Lyrid stream, like some which appear xx. p. 201 , May, ,g97 . ' ' NU. 1747, VOL. 67] © 1903 Nature Publishing Group