254 



KNOWLEDGE. 



[NOVEMBEK, 1903. 



AsTEONOMicAL. — Auotlier contribution to the study of 

 the relation lietween solar activity and terrestrial magnetism 

 was set fortli by Father Cortie in a jiaper read at the recent 

 meetins; of the British Association The point to which 

 special attention was given was to determine if large and 

 violently eruptive prominences, in the absence of spots, 

 were responded to by magnetic disturbances, and from a 

 discussion of the prominence observations for the years 

 1887-8?^ it was found that in no single case could a 

 magnetic storm be definitely associated with any particular 

 pi-ominence outburst, while great eruptive prominences 

 occurred with no accompanying magnetic storm. It is 

 concluded that the earth's magnetism is not affected 

 directly by any particular spot or prominence, but by the 

 general disturbance of the suq and his surroundings. 



In an interesting letter to The Observafory, Mr. J. E. 

 Gore draws attention to a description of Sirius given by 

 Al-Sufi, the Persian astronomer in the tenth century. It 

 is stated that " the Arabians call the brilliant and great 

 star which is in the mouth al-schira al-ahnr, Sirius which 

 has passed across. ... It is called ul-abur because it has 

 passed across the Milky Way into the southern region." 

 Mr. Gore points out as a remarkable fact that the proper 

 motion of Sirius (l''-31 per annum in the direction of 

 position angle 204^) would have carried it across the 

 Milky Way in about (lO.OOO years, and suggests that a 

 mythological story related by Al-Sufi as to why Sirius fled 

 towards the south may be based on a tradition of Sii'ius 

 having been seen on the opposite side by men of the Stone 

 Age. At all events, the Arabic name al-ahur denotes an 

 actual fact. Al-Snfi further says that when Sirius passed 

 across the Milky Way, Procyon remained in the region to 

 the north-east of the Milky Way, which is also accordant 

 with the known amount and direction of the proper motion 

 of this star; 60,000 years hence, Procyon will also have 

 crossed the Milky Way. — A. F. 



Method foe Ascertaining the Moon's Age. — Mr. 

 Holmes' method for ascertaining the moon's age may be 

 explained in the following manner. It depends, first of 

 all, on the " Metonic cycle." Nineteen solar years corre- 

 spond to 235 lunations ; hence the new moons in one year 

 correspond to those in the years IP years earlier or 19 

 years later. This gives the first part of the rule, the effect 

 of which is to divide all years into 19 classes, and corre- 

 sponds in eff'ect to the finding of the " Golden Number." 

 The relation of any one year of a Metonic cycle to the 

 next year of that cycle is given \>y the '* Epact " — the age 

 of the moon on the first day of the year. Since twelve 

 lunations include 354 days, and a solar year 365 days, the 

 epact of any year is 11 days greater than that of the pre- 

 ceding year. When the epact amounts to more than an 

 entire month, only the odd days are counted. This gives 

 us, in effect, the second jsart of the rule. There remains 

 only the last part. January and February together make 

 uj) two complete lunations. For the remaining months of 

 the year, each is on the average one day longer than a 

 complete lunation, so that the day of the new moon, on the 

 avercKje, falls one day earlier in each month after March. 

 The year 1900 is divisible bj' 19 without remainder, and in 

 this year the first new moon fell on January 1, so that for 

 the month of January the day of the month gave at once 

 the age of the moon. The rule then follows from the 

 above principles. It is necessarily quite a rough one, and 

 will often be two days in error, but as an instantaneous 

 way of getting an approximate idea of the moon's age, it 

 has its use. — E. W. M. 



Zoological. — Those of our i-eaders who studied the 

 articles on "The Palajontological Case for Evolution" 

 recently published in this journal should be interested in a 

 memoir on the ichthyosaurs, or fish-lizards, of the Triassic 

 strata of California, issued in the Geological Bulletin of the 

 Californian University. Compared with their descendants 

 of the Lias, these Triassic species were quite small. Their 

 most interesting feature is, however, the structure of the 

 paddle, in which the component bones are much more 

 elongated, and therefore less unlike the coi-responding 

 elements of nomial reptiles, than are those of the true 

 ichthyosaurs of the Lias. An important step is thus made 

 in tracing the origin of the group. 



Unlike chimpanzees, which have long since been recorded 

 from Uganda, gorillas have hitherto been supposed to be 

 confined to the west coast of Africa. Much interest 

 attaches therefore to the discov ry of a representative of 

 these ajjes high up on Mount Kirunga, nearly midway 

 betweeu Lakes Albert Edward and Kivu. Dr. Matschie, 

 of Berlin, has described the animal as Gorilla heriuyei. 



Mr. Pycraft's memoir on the osteology of owls, recently 

 published in the Transactions of the Linnean Society, is 

 an important contribution to our knowledge of birds' 

 skeletons. Had we to deal with the skeleton alone, it is 

 2)robable that owls would never have been separated in 

 systematic zoology from the diurnal birds of jjrey. The 

 soft parts are, however, very different in the two groups, 

 and all the evidence points to the near affinity of the owls 

 to the goat-suckers. Yery curious is the discovery that 

 the Nepalese horned owl differs from all its relatives in 

 regard to the notching of the breast-bone. Whether, 

 however, this necessitates its reference to a genus apart, 

 may be a matter of opinion. 



Some years ago an article, by Mr. Lydekker, appeared 

 in this journal on the nursing habits of frogs. In the 

 October issue of the Zoological Society's Proceedings, Mr. 

 Boulenger describes the mode in which the eggs are 

 carried by the female of a rare frog (Ceraiohyla bubaltis) 

 from the Peruvian Andes. In the one specimen obtained 

 with eggs, there were nine of these tightly adhering to the 

 skin of the back, in which the spines of the verteVirae were 

 so prominent as to leave indentations in the egg- 

 membranes. Fully-formed young frogs were seen in the 



Errat.v. — In Mr. A. C. D. Crommelin's articles on Cycles of Eclipses in 

 KxowLKDiiE for September, p. 205, 2nd column, 5th line from bottom, for 

 " N. Dec. 91^*^ 27 ," read ". N. Deo. 9' 27 " ; for October, p. 226. description 

 under Plate IV., for " K*5 vears earlier." read " 1805 veurs earlier." 



33ritist) ©rnitijolosical Notes. 



Conducted by Hajrrt F. Witherbt, f.z.s., M.B.o.tr. 



Sooty Tern ('Sterna fuliginosi, G-m.) in SufolJc {Field, October 

 3rd, 1903, p. 600).— Mr. W. A. Dutt here records that he lately found 

 a fine adult specimen of this Tern in the possession of Mr J. Xuun, 

 of Santon, Downliam. The bird was found dead at Santon Downhain 

 Warren in the spring of 1900. Mr. Thomas Southwell has confirmed 

 its identiScatioc. The Sooty Tern is an inhabitant of the Pacific, 

 but it occurs as far west as the Indian Ocean and the Red Sea. It is 

 a rare wanderer to Europe, and has only been recorded three times, 

 previously to t!ie above instance, in Kngtand. 



Hartford Warhhr in Shropshire {Zoologist, 1903, September, 

 p. 349). — Mr. H. E. Forrest records that a pair or two of Dartford 

 Warblers has been found breeding near Ludlow, in Shropsliire, this 

 summer. This is a north-western extension of the known breeding 

 range of this bird. It is a species easily overlooked, owing to its 

 secretive habits, and it is quite probable that Dartford Warblers 

 have long made use of this newly-found breeding place. 



Tree Sparrow in Shetland {Ann. Scot. Nat. Hist., 1903, p. 211) 

 iind in the Isle of Man (Zoologist, 1903, p. 313). — For some years 

 the Tree Sparrow has been extending its range. Fifty years ago it 

 was unknown in Ireland, but it is now resident and increasing in 

 numbers there. Mr. Jf. S. Graves now reports it from the Isle of 



