January, 1907.] 



KNOWLEDGE & SCIENTIFIC NEWS. 



great earthquake rift, which extends through the coast 

 range of CaHfornia, for a distance of 200 miles, follows 

 a direction, which, if produced northward to Behring 

 Sea, would pass near the islands of Bogoslof. Again, 

 this earthquake rift was largest, and its effects more 

 violent, where it entered the sea in Mendocino County 

 than at any other point throughout its course, the ex- 

 tent of the lateral movement along the crack increasing 

 from about two feet in Monterey County, to about i6i 

 feet at Point Arena, where it finally enters the sea. 



" In opposition to this view may be placed the im- 

 probability that an earthquake rift or fault would ex- 

 tend so far as from the centre of California to Behring 

 Sea, a distance of more than 2,000 miles, and through 

 such depths of water as intervene between Point Arena 

 and Bogoslof. It is also stated that the evidence of the 

 seismograph, so far as understood, favours the idea 

 that the great earthquake was confined to California, 

 although its centre of disturbance was clearly in the 

 sea in a westerly direction from Cape Mendocino. 



" It is evident, also, that the ri.se of the third Bogoslof 

 was attended by little, if any, disturbance in the im- 

 mediate vicinity. The advent of each of the other two 

 islands was marked by earthquake shocks, the fall of 

 volcanic ashes, and displays of fire, observed and felt 

 by the people of Iliuliuk, on Unalaska Island. The 

 people of this village in 1906 were unaware of the 

 presence of the new island until the news was brought 

 in by vessels touching at the harbour." 



On the whole, the weight of evidence at present 

 seems to favour the idea that the Bogoslof disturbance 

 of igo6 was local in character, and the coincidence in 

 date with the California earthquake involves no actual 

 relation between the two phenomena. 



The January Eclipse of the Sun. 



It is truly unfortunate that the tot:d eclipse of 1907 

 January 13-14, whose totality track has the rare advan- 

 tage of being entirely on land, should fail so lament- 

 ably in other ways as to be practically disregarded in 

 this country. The reasons, or some of them, are not 

 far to seek, for the track commences not far from the 

 Northern extremity of the Caspian Sea, and, curving 

 in the familiar manner of eclipse tracks through E.S.E., 

 E., and E.N.E., finally reaches a point among the south- 

 etistern head waters of the Lena Basin, not far from 

 the Gulf of Okhotsk. Even in mid-summer, a consider- 

 able portion of the track over the " roof of the world," 

 is considered inaccessible, but in mid-winter, the oc- 

 cupation of more than a few of the most favourable 

 points is unthinkable. In Western Turkestan, where 

 the line of totality goes nearly a thousand miles further 

 south than London, there would ;ippear to be the best 

 chance of reasonable conditions, but most of the land 

 lies so high in Central -Vsia that bitter cold is almost 

 a certainty, though in a few sheltered valleys it will 

 be less rigorous. Communication is better than it 

 was a few years ago, for there is direct railway con- 

 nection with Europe via Moscow and Orenburg to 

 Tiishkent, .ind between that Ob.servatory and 

 Sainarcand are several stations not far from the 

 central line, of which, |)erhaps, Jizak is the most access- 

 ible. Tsairosu, in Mongolia, is the only station 

 further East than Turkestan that has been suggested 

 for occupation, hut the princip.il expeditions will bo 

 Russian, and of these M. Hansky's is sure to be well 



to the fore. There are expeditions planned from Ger- 

 many, under the auspices of Dr. Schorr, of Hamburg, 

 and from France, equipped by the Bureau des 

 Longitudes. Many will remember the success that at- 

 tended the Russians and others at the ill-fated eclipse 

 of 1896, but that was in August. We can only hope 

 that the results on the present occasion will be com- 

 mensurate with the zeal of those who are braving the 

 unpromising conditions. Doubtless, had an official 

 expedition been .sent from England, several enthusiastic 

 amateurs would have been prepared to accompany it 

 if possible, the more so that the chances of success in 

 January 1907, though perhaps not encouraging, are 

 quite as good as, and in many ways better than, those 

 of any other eclipse in the next five years, which will 

 be singularly barren in that respect. 



The present eclipse belongs to a series (recurring at 

 the well-known period of 18 years 11 days"), whose 

 first member was the celebrated Siege of Paris eclipse 

 of December 1870, when Janssen escaped from Paris 

 in a balloon in order to observe the eclipse in Algiers, 

 and saw nothing of it owing to cloud. 



A Perpetual Calendar. 



By Charles E. Benham. 



The practical utility of a simple method whereby, with- 

 out pencil, paper, or reference table, one is enabled 

 to tell almost in a moment the day of the week for any 

 given date is so great that anyone who has been at the 

 small pains necessary to master the process will never 

 repent of having done so. On the contrary, he will 

 only wonder that a formula so simple and so advan- 

 tageous is not made a part of the regular curriculum of 

 every elementary school. 



At a first glance the system prescribed may seem a 

 little complicated, but with very little practice it be- 

 comes perfectly easy and simple, while anyone with a 

 natural talent for mental arithmetic may speedily ac- 

 quire ability to perform the process with such rapidity 

 that his powers seem, to the uninitiated, little short of 

 magical. 



The method depends primarily upon a system of 

 casting out the sevens, that is, dividing by seven and 

 taking only the remainder. Thus, 24, when the sevens 

 are cast out yields 3; 21, o; 40, 5; and so on. 



Bearing tliis in mind, the process for a perpetual 

 calendar is simply to add together four numbers, repre- 

 senting respectively century, year, month, and day of 

 month, casting the sevens out as the addition proceeds. 

 Thus, if those four numbers were o, 23, 6, 14, we 

 should add together o, 2, 6, and = 8, or, casting out 

 the sevens, i, which would mean that the date in ques- 

 tion was on the first day of the week, or Sunday. 



But what we have to arrive at is how to ascertain 

 the four appropriate numljers for a given century, year, 

 month, ajid day. 



The rule is as follows : — 



(i) For the Century Numbers. — These must be 

 memorised, 2 for the century 1800-99, o for 1900-99, 

 and 6 for 2000-99 These are thus fixed for con- 

 venience, because the system Ix^ing calculated on this 

 basis, the o for tiie present century, which is most 

 likelv to be wanted, will sa\e calculation. Tliis ar- 

 rangement is a modification, by Mr. Robert Cook, of 

 Chelmsford, of Howard's Per|>etual Calendar, in which 

 the o was fixed for the previous century. 



