June 26, 1879] 



NATURE 



205 



Passage through perisaturnium, 1S52, Nov. i7"52oS 

 G.M.T. 



Perisaturnium 240° 10' '9 



Excentricity 0T2011 



Semi-axis major ... 2l7"'o5 



It will be seen that the position of the perisaturnium had 

 undergone a great change in the interval between the 

 above epochs : the rapid motion of the line of apsides has 

 been known for some time past to those who have 

 attempted the determination of elements of Hyperion. 

 Prof Hall had at first supposed this motion direct, but he 

 now adopts the smaller retrograde motion, and so finds for 

 the motion of the line of apsides in a Julian year, — 

 2°'92S62. If we assume that 394 revolutions of the 

 satellite had been performed in the interval between the 

 epochs (8379'3i72 days), the anomalistic period is found 

 to be 2 1 •2673026 days. 



Prof. Hall thinks that the next step must be the 

 calculation of the action of the great satellite Titan on the 

 motion of Hyperion, a w^ork which he hopes to be able to 

 undertake. Not only is there a near approach of the 

 orbits of the two bodies, but it would appear that 

 Hyperion is moving in a larger orbit, than would corre- 

 spond to the assigned period and Bessel's mass of Saturn. 

 There is a probability that the approximation of the two 

 satellites may be, at certain times, very close indeed. 

 If we bring up Bessel's elements of Titan to 1875, and 

 compare them with the above elements of Hyperion for 

 the same year, we find an exceedingly near approach of 

 the two bodies, when the position of the perisaturnium of 

 Hyperion corresponds to that of maximum distance of 

 Titaa, and though uncertainty in the elements may affect 

 the result, it is sufficiently evident that the motion of 

 Hyperion cannot be followed satisfactorily without a 

 knowledge of the action of Titan. Prof. Hall remarks 

 that in 1882 it may be possible with the Washington 

 refractor to follow Hyperion completely round its primary, 

 as was done by Mr. Lassell at Valetta in 1852, and that 

 from that time until 1888 it should be carefully observed. 



The Oxford University Observatory.— The report 

 of the Savilian Professor of Astronomy, as Director of the 

 University Observatory at Oxford, has been issued, for 

 the year ending on the 4th of the present month. The 

 I2.| inch refractor has been in constant use in the deter- 

 mination of accurate positions of about 40 stars in the 

 Pleiades, partly with the view of ascertaining the proper 

 motions by comparison with the observations of Bessel 

 half a century ago, and partly with the intention of 

 comparing the micrometrical measures with those of the 

 costly heliometer. The results will appear in Part II. of 

 the Oxford Observations, and we may remark that the 

 Savilian Professor will have a recent standard for com- 

 parison in M. Wolf's elaborate work on the Pleiades, 

 {Description dii Croupe des Pleiades in the Paris Annales, 

 t. xiv.), to which he has not made allusion in the report. 

 The De la Rue reflector has been employed in taking 

 photographs of the moon, and nearly three hundred have 

 been secured. With the view of ascertaining how far 

 these photographs can be relied upon for accurate 

 measurements, micrometrical measures of the shadows 

 of several prominent lunar mountains were made with 

 the refractor, simultaneously with the taking of photo- 

 graphs with the reflector ; the latter being then measured 

 in the De la Rue engine, it was found that the telescopic 

 and photographic results were in close accordance, indeed 

 within the limits of the unavoidable errors of observation. 

 The Professor adduces a still further proof of the reliability 

 of celestial photography in this direction, in the close 

 accordance of the moon's semi-diameter, as measured 

 arid computed from sixteen of the Oxford photographs 

 with Hansen's value adopted in •Ca.t. Nautical Almanac ; 

 the difference is only a''i2. Amongst the other mis- 

 cellaneous work of the Observatory during the past year, 

 the periodical comets of Tempcl (1873 July) and Brorsen 



have been well observed. In the Lecture Room discourses 

 have been delivered on the Astronomy and Astronomical 

 Instruments of Ptolemy and Hipparchus, on the Physical 

 Libration of the Moon and on Solar Physics. 



The obligation under which this institution remains to 

 the great liberality and scientific spirit of Dr. De la Rue 

 is well known. The salary of the photographic assistant 

 has been defrayed by him during a period of four years, 

 this subsidy, a most important one to the rising Observa- 

 tory, terminating in December next. The necessary 

 provision for the future effective conduct of the Observa- 

 tory is under the consideration of the University Commis- 

 sioners, subject to the final judgment of Convocation. It 

 is suggested by the Savilian Professor in his report, that 

 for the next few years a sum of 600/. annually may suffice 

 to cover all necessary expenses. The desirability of an 

 early publication of results, in the actual state of Astro- 

 nomical Science, appears to be fully appreciated in the 

 Oxford establishment : part I. of the Observations con- 

 taining the work to December 1877 was published in the 

 spring of 1878. 



A New Comet. — A pretty bright telescopic comet was 

 detected, apparently on the i6thinst.,by Mr. Lewis Swift, 

 of Rochester, N.Y. Prof. Winnecke observed it at 

 Strasburg on June 21, and found its position at iih. 38m. 

 46s. mean time in R.A. 2b. 47m. 31 "is., Decl. 64'-' 29' 5"; 

 daily motion in R.A. trifling, that in Decl. about one 

 degree towards the north ; diameter about three minutes. 



GEOGRAPHICAL NOTES 



At the meeting of the Royal Geographical Society on 

 Monday evening, after a feeling allusion by the Earl of 

 Northbrook to the loss sustained by the Society by the 

 death of Mr. R. B. Shaw, British Resident at Mandalay, 

 who was well-known for his excellent geographical work 

 in Eastern Turkistan, &c., some reports were read which 

 had recently been received from Mr. Keith Johnston, the 

 leader of the East African Expedition. The first was an 

 exceedingly interesting account of his preliminary trip 

 from Zanzibar to the Usambara Hills, and the second 

 was a memorandum of information obtained regarding 

 routes between Dar-es-Salaam and the north end of Lake 

 Nyassa. It is no exaggeration to say that the latter 

 document contained more real geography than many 

 travellers contrive to collect in the course of a long 

 journey, and it confirms the impression that Mr. Johnston, 

 if he be spared, will, on his return from the interior, furnish 

 us with a most admirable and accurate account of the 

 country traversed, the greater part of which is at present 

 absolutely unexplored. The Secretary afterwards read 

 letters from Mr. Johnston and Dr. Kirk, H.M.'s Consul- 

 General at Zanzibar, announcing the final start of the 

 expedition for the interior, under the most favourable 

 circumstances. Mr. Johnston has with him one European 

 assistant and 138 porters, who have been carefully selected 

 with the aid of Chuma, Livingstone' s old follower, who 

 also accompanies the party. 



The last sitting of the Geographical Society of Paris, 

 was devoted to a lecture given by M. Cosson to prove 

 (i) that M. Roudaire's contemplated Algerian sea would 

 not improve the climate of the Sahara ; (2) that in case 

 any alteration were possible it would be detrimental to the 

 health of the inhabitants; (3) that it would create dis- 

 satisfaction amongst the Tunisian and Algerian tribes, 

 and even Algerian colonists ; and (4) that it would have uo 

 effect in attracting to Algiers the trade of the Soudan. 

 Commander Roudaire not having been invited to answer 

 the charges proffered against his scheme the discussion 

 was adjourned, but several members warmly protested 

 against the assumption brought forward by M. Cosson, 

 and tried to rebut his assertions. 



Captain R. H. Napier, R.N., has communicated 

 some useful hydrographic notes to the Hong Kong 



