May 



1907] 



NA TURE 



87 



daily range of the amount of positive ionisation showed a 

 principal maximum at iih. a.m., that of the negative at 

 3h. a.m. The minima agreed fairly well in time, the posi- 

 tive occurring at 3h. p.m. and the negative at ah. p.m. 

 A secondary maximum of the positive at 4h. a.m. occurred 

 near the time of the principal negative maximum, while 

 a secondary maximum of the negative, at iih. a.m., 

 occurred at the time of the principal positive maximum. 



In Metcorologische Zeitschrift (No. 12, 1906) Dr. A. 

 de Ouervain urges several arguments in favour of the 

 real existence of the inversion of temperature at the height 

 of 8-13 kilometres, upon which doubt has been thrown 

 by several persons. M. Tei.sserenc de Bort instituted a 

 number of ascents at Trappes (near Paris) during the night 

 or early morning, so that the unmanned balloons might 

 reach their greatest heights before sunrise, which seem 

 to show without doubt the real existence of the inversion. 

 Dr. de Ouervain points out that in the international ascents 

 made during the daytime at Strassburg, St. Petersburg, 

 and Zurich (as well as other places), every possible care 

 has been taken to eliminate the effect of radiation, and 

 that the results also fully support the reality of the in- 

 version. There is also the fact that a stratum of air is 

 frequently found above the inversion zone, where the 

 temperature again decreases decidedly with increasing 

 altitude. 



We have frequently had occasion to refer to the useful 

 work of the Zi-ka-wei Observatory, near Shanghai, in 

 issuing timely notice of the approach of dangerous storms. 

 At the present time it receives telegraphic reports from 

 several of the Chinese stations, and telegrams twice or 

 thrice daily from thirty-two foreign stations, obligingly 

 forwarded with the consent of their respective Govern- 

 ments. Telegraphic storm warnings are sent from Zi-ka- 

 wci to some fifteen of the principal Chinese ports, nearly 

 all of which have semaphores which exhibit storm signals ; 

 notices are also transmitted to Vladivostock, Tokio, 

 Formosa, and Indo-China. The Inspector-General of 

 Chinese Customs has, at the urgent request of the director 

 of the observatory, further sanctioned the erection of 

 semaphores at twenty-five selected lighthouses not yet 

 electrically connected, to which, from May, 1907 — about 

 the time of the beginning of the typhoon season — captains 

 of ships leaving port are invited to repeat, during the day- 

 time, the warning notices they have seen in the harbours 

 for the benefit of the fishing and other small craft in the 

 ofTJng. 



In view of the approaching tercentenary of the discovery 

 of logarithms. Dr. F. H. Loud contributes a note to the 

 semi-annual Bulletin of the Colorado College Observatory 

 in which he proposes several rapidly converging series, 

 and shows how they might be used for the re-calculation 

 of logarithms to a large number of decimal places. A 

 table is given of logarithms of primes below no to 

 eighteen places. 



Mr. Ch.arles Urb.in issues a pamphlet recommending 

 the use of the kinematograph for scientific and educational 

 purposes. He has published a large number of rolls 

 demonstrating living objects, such as pond life as seen 

 through the microscope, and it is suggested, among other 

 uses, that the kinematograph may be applied to take 

 records of important surgical operations for future use in 

 class demonstration, and also to exhibit to medical 

 students the details of experiments on living animals with- 

 out repeating the actual experiments before every fresh 

 batch of students. 



\o iq6o, vol. 76] 



Prof. E. W]edem.\n-n is well known for many contribu- 

 tions he has made to the subject of Arabian astronomy. 

 In a recent communication to the Physikalisch-Medizin- 

 ischen Society of Erlangen he gives the translation of a 

 paper from the Qasid al Irschad, " Guide to the Aspir- 

 ing," to which his attention had been directed by Prof 

 Nallino, of Palermo. The original author, who seems to 

 have been indifferently known as al Ansari or al SachElwJ, 

 was a competent exponent of the astronomy of his day. 

 Astronomy he describes as the science which teaches the 

 nature of separate bodies, their figures and positions, the 

 distances between them, the motions of the planets, and 

 the magnitude of the heavenly bodies. Four fundamental 

 parts are recognised. In the first is investigated what is 

 common to all spheres or orbits, the words seem to have 

 the same significance, to the relations between them, and 

 the proof that they all move, the earth remaining at rest. 

 In the second is demonstrated the character of the motions 

 of the heavenly bodies, how many there are, the divisions 

 of the zodiac, and the phenomena of the eclipses. The 

 third treats of the earth and of the climate in different 

 places, and of the differing lengths of the day and night 

 according to latitude. The fourth part considers the 

 magnitude and the distances of the stars. References are 

 made to classical works in which these subjects can be 

 studied at greater length. Further subdivisions follow, 

 having reference to the calculation of ephemerides, the 

 calendar, the method of observing, the projection of the 

 sphere, and problems connected with the gnomon. Into 

 these it is scarcely necessary to follow either the learned 

 Arabian or his able translator. The paper is interesting, 

 but its scientific value is mainly confined to the elaborate 

 notes with which the author has enriched his translation. 

 These notes are both philological and historical. 



Students of the early history of science will find an 

 elaborate and interesting discussion of Petrus Peregrinus 

 de Maricourt's " Epistola de Magnete, " by Prof. S. P. 

 Thompson, in vol. ii. of the Proceedings of the British 

 Academy. Petrus Peregrinus, we learn, was a native of 

 Picardy, a friend of Roger Bacon, and a man of very 

 varied knowledge for his time. The " Epistola " is 

 believed to have been written in August, 1269, while its 

 author was assisting in the siege of Lucera, in southern 

 Italy. Peregrinus's chief claim to distinction, in Prof. 

 Thompson's opinion, was his invention of improved forms 

 of the compass. One form, like earlier compasses, was 

 floated in water, but it was the first to possess the equi- 

 valent of a " lubber " line and a divided circle. A second 

 form was pivoted, and may be regarded as the precursor 

 of the azimuth compass. An even more curious instrument, 

 which, though illustrated, was presumably never 

 materialised, was to consist of a light pivoted circle, having 

 a number of inwardly directed iron teeth, with a fixed 

 lodestone at its centre. Peregrinus's hope was to secure 

 perpetual motion. There seems here almost an anticipa- 

 tion of one idea at least embodied in the dynamo, but 

 Prof. Thompson is too experienced a writer to enter on 

 this theme with an audience where his remarks would 

 be liable to misconstruction. The discovery of the declin- 

 ation of the compass from true north has been ascribed 

 by some to Peregrinus, but this Prof. Thompson says is 

 a mistake, arising from a spurious addition made to a 

 Leyden MS. of the " Epistola " about the end of (he 

 fifteenth century. In Appendices A and B Prof. Thompson 

 enumerates the various MSS. and printed versions of the 

 " Epistola." Of the tweirty-eight MSS. enumerated, it is 

 surprising to find that no fewer than twelve are in libraries 

 situated in the United Kingdom, seven being in the 



