NATURE 



[August ii, 1910 



on May 5, the former of which shows a tail 20 miUion 

 miles long. 



Some extraordinarv phenomena were observed at \ ictoria 

 (B.C.) at about 7 p.m. (local M.T.) on May 18. The sun 

 appeared to be in a state of rotation, emitting bright 

 flashes of light at frequent intervals. These were prob- 

 ably unusual refraction phenomena, possibly produced by 

 the interposition of cometary matter, and are recorded by 

 an octogenarian, Mr. Helmcken, who has never seen 

 similar phenomena before. 



In No. 8, vol. Ixx., of the Monthly Notices there are 

 more than a dozen papers dealing with observations of 

 the comet's position, its physical characteristics, and its 

 spectrum. 



The Rivista di Astronomia, No. 6, contains some ancient 

 records of the comet, reproduced by Father Stein, one of 

 which shows that Halley's comet was observed in Italy 

 for about fifty days in 1066; it became lost in the solar 

 rays on .^pril 19, and reappeared, as an evening star, on 

 April 24. 



The Accurate Measurement of Photographs. — In all 

 photographic astronomical researches the results are more 

 or less vitiated by errors introduced by the optical apparatus, 

 including the eye and brain of the observer, employed in 

 their reduction. To eliminate these errors, Prof. E. C. 

 Pickering proposes, in Harvard College Observatory 

 Circular No. 155, the employment of an automatic 

 registering apparatus. Briefly, he suggests that the 

 negative to be measured be passed between a constant 

 illumination and the two balanced arms of a bolometer. 

 As the star image, or spectral line, comes in between the 

 heat source and the bolometer, some heat would be cut 

 off, and the galvanometer in the circuit would show a 

 deviation, which could be registered automatically. The 

 galvanometer curve would thus become a record of the 

 positions and intensities of the star images or the lines in 

 the spectrum, and the method, especially for spectrum 

 work, should certainly be tried by someone having the 

 necessary bolometric apparatus or selenium cells at their 

 disposal. 



Observations of Perseids in 1909. — In No. 31, vol. 

 iii., of the Mitleihingen der Nikolai-Hauptstermvartc zii 

 Pulkowo, Horr S. Beljawsky describes the observations of 

 Perseids made at Simeis on .August 10, 11, and 12, 1909. 

 The horary rates of the meteors observed on these three 

 dates were 21, 60, and 17 respectively, and the positions 

 of the radiants were 49°, + 60° (s obs.) ; 45°, + 56° 

 (15 obs.); and 43°, +55° (8 obs.), respectively. On 

 August II there appeared to be another radiant at 62°, 

 + 16°, from which four meteors appeared to emanate, but 

 the determination is uncertain. 



Results from the Micrometric Observations of Eros, 

 1900. — During the opposition of Eros in 1900, a number of 

 observers made micrometric comparisons between the 

 planet and neighbouring stars. The results from a 

 number of observatories have been reduced at Cambridge, 

 and Mr. Hinks now discusses them in No. S of the Monthly 

 Notices. The individual results agree generally, and give 

 as the most probable value for the solar parallax 

 8>8o6' + 0-004. 



WILD PLANTS ON WASTE LAND IN LONDON. 



THE waste ground between .'Mdwych and the Strand has 

 been colonised by a variety of plants, most of which 

 show luxuriant growth. Many of the colonists have fruits 

 or seeds adapted to wind distribution, as in the case of the 

 winged fruit of the sorrel (Ruincx acetosa), and of the 

 plumed seeds of the hairv willow herb (Epilobium hirsutum) 

 and French willow, or rose bay (£. nngustifolium), hy far 

 the most conspicuous plant on the ground. It is of interest 

 that E. angusti folium, which is absent in many of the 

 waste places of London, occurs in the garden of Fountain 

 Court, near the Strand. Among wind-distributed forms 

 are also numerous Compositse, the fruits of which are 

 furnished with a pappus ; these include the spear thistle 

 {Cirsum lance olatum), the groundsel {Senecio vulgaris) and 

 its ally S. viscosus, the dandelion (Taraxacem -ndgare), 

 the butter bur {Tussilngo petastcs), and the Canadian flea- 



NO. 2128, VOL. 84] 



bane (Etigeron canadensej. Fruits and seeds of these 

 various types might be blown with some readiness from 

 neighbouring districts, or from one part of London to 

 another. 



To a varying extent, wind may be also efficient in carry- 

 ing the seeds of hedge mustard (Sisymbrium ofjiciuale), 

 London rocket (S. irio), which appeared in quantity after 

 the Great Fire of 1066, and shepherd's purse (Capsella 

 bursa pastoris) ; and the same is the case with chickweed 

 {Stelloria media), white campion {Lychius alba), opium 

 poppy (Papavcr somnijerum), a garden escape, frequently 

 established in waste places, great plantain (Planiago 

 major), pale persicaria (Polygonum lapathifolium), and 

 scentless mayweed (Matricaria inodorata). In several of 

 the above the seed is small or flattened, but it is not 

 elaborately adapted to wind dispersal, and it may be 

 questioned whether wind alone will account for the presence 

 of these plants. A probable auxiliary exists in the sparrow, 

 through the alimentary canal of which various seeds and 

 fruits no doubt pass, and it is not unlikely that others 

 become attached to its feet by means of the sticky London 

 mud. It will be remembered that Darwin in the " Origin 

 of Species " describes eighty-two plants as springing from 

 the earth obtained from the feet of a single partridge. 

 This method of distribution no doubt accounts for the 

 presence of Dutch or white clover (Trifolium repens) and 

 of two balsams, the pink-flowered Impaliens glandulifera 

 and a white variety. The explosive fruit characteristic of 

 this genus could certainly not shoot its seeds across the 

 traffic of a London street. Possibly cats may be effective 

 as agents of distribution in this case, and they may also 

 account for the presence of cleavers (Galium Aparine), the 

 hooked fruits of which would readily cling to their fur. 



Among garden escapes, the marigold, nasturtium 

 ( = Trop£eolum), wallflower, and a species of Prunus can be 

 observed, as well as the opium poppy mentioned above ; in 

 connection with these, and with many of the wild species 

 also, the neighbourhood of Covent Garden must be re- 

 called. 



The above list is by no means exhaustive, none of the 

 grasses, for instance, having been mentioned ; in one or 

 two cases the identification had to be made from a distance 

 and through the fence surrounding the waste ground. 



AGRICULTURAL INVESTIGATIONS IN 

 EGYPT.' 



SEVERAL important events are chronicled in the current 

 " Vefir-book of the Khedivial Agricultural Society." 

 The scope of the society has recently been extended by the 

 formation of a section dealing with farm animals, the 

 object of which is to effect as much improvement as 

 possible in the livestock of the country. Twenty stallions 

 have already been distributed over the country, a number 

 of selected cows have been acquired from which good stud 

 bulls can in time be sent out, and a herd of buffaloes has 

 been purchased with a view to the establishment of a heavy 

 milking strain. In addition, an experimental farm of 

 about 160 acres has been acquired near Cairo, and an 

 arrangement has been effected with the State Domains 

 .Administration whereby a considerable tract of land is to 

 be set aside for the raising of cotton or wheat seed of good 

 quality. Finally, the society has directed attention to the 

 diminished yield of cotton in proportion to the area sown. 

 A committee was appointed to investigate the matter, and 

 has already issued a report. 



A considerable proportion of the year-book is taken up 

 by Mr. Lawrence Balls's studies of Egyptian cotton. A 

 detailed account is given of the results of a single cross 

 made in 1905 between ."Vfifi and Truitt Big Boll. The 

 fourth generation is now growing, and, although the cross 

 has no special economic value, and the results are in some 

 ways incomplete, the record is a very valuable one, and 

 throws much light on production of cotton varieties on 

 Mendelian lines. The synthesis of a commercially useful 

 cotton is a tedious business. Desirable characters are 

 mostly dominant over undesirables, except where the 



1 The Year-Book of the Khedivial Agricultur.->I .Society, Cairo, 1909. 

 Pp. xv + 239. (Glasgow: The Universiiy Press. 1910.) 

 The Cairo Scientific Journal. Vol. iv., No. 43. 



