298 



NATURE 



\yan. 30, 1890 



continuous, though theyare sometimes as bright as true magnetic 

 auroras which show the citron line. 



The average number of nights on which I have seen these 

 irregular auroras in the past 28 years, chiefly at Sunderland, is 

 I "9 per annum ; and, if doubtful cases are included, 2*7, They 

 agree with magnetic auroras in so far as they show some 

 tendency to an eleven-year periodicity, being most frequent 

 about 2 years after the sun-spot maximum, and least so about 5 

 years later. T. W. Backhouse. 



Sunderland, January 15. 



Mr. Stromeyer's letter in Nature of the 9th inst. (p. 225) re- 

 minds me of a magnificent display that I once saw of luminous white 

 clouds, transparent to the stars, which shone brightly through 

 them. These clouds were extended Hkc ribbons from north to 

 south across the sky, in a way not uncommon with true clouds. 

 I thought, and still think, that they were an aurora. May not 

 those described by Mr, Stromeyer have been the same? 



Belfast, January 15. Joseph John Murphy. 



The Meteorite of Mighei. 



With reference to the interesting meteorite of Mighei, ex- 

 amined by M. Stanislas Meunier, I have not observed, in any of 

 the notices I have seen, any statement as to whether the organic 

 matter exhibited any traces of an organized structure. I would 

 suggest that, if it has not already been done, it should be care - 

 fully examined to see if the carbonaceous matter shows any such 

 traces. J. Rutherford Hill. 



January 11. 



Achlya. 



I shall be very grateful to any of your readers who can send 

 me specimens of Achlya with the sexual reproduction, which I 

 cannot at present obtain in my cultures. The culture should be 

 dropped bodily into a cold saturated solution of corrosive sub- 

 limate, in a wide-mouthed corked bottle, and this filled up with 

 the liquid to the cork before posting. 



Marcus M. Hartog. 



5 Roseneath Villas, Cork, January 6. 



The Parallelogram of Forces. 



What is the force of the word "rigid," introduced into the 

 statement and proof of the parallelogram of forces and other 

 theorems in Statics, as quoted by Mr. W. E. Johnson from the 

 ordinary text-books ? 



The word " rigid " requires definition ; it describes a state of 

 things which is not met with in Nature ; and it is redundant and 

 limiting ; because the conditions of equilibrium of a body are the 

 same, whether elastic to an appreciable extent, or to such an 

 inappreciable extent that the word "rigid" may be aiDplied 

 to it. 



Better omit the word ' ' rigid " altogether. 



A. G. Greenhill. 



Foot-Pounds. 



In the statics and dynamics paper set in the last Woolwich 

 entrance examination, candidates are asked to determine the 

 magnitude of a moment of a force m. foot-pounds. Surely it is 

 unfortunate to introduce this term in such a sense. One 

 foot-pound is a unit of work, and though its dimensions 

 (ML^T--) are the same as that of a unit of a moment of a force, 

 the two conceptions are perfectly distinct, and the introduction 

 of a foot-pound as a unit of a moment of a force is likely to 

 cause confusion, especially in the minds of beginners. 



A. S. E. 



Chiff-Chaff singing in September. 



In a review of certain recent ornithological works, in one of 

 your latest issues, doubt seems to be thrown on the fact of the 

 chifF-chaff singing late in September. 



I believe it is not an unusual occurrence. It always nests in 

 my garden, and this year, as I see by a note made at the time, 

 it sang on the 20th, 21st, and 22nd of that month. We had a 

 slight frost on the 21st. F. M. Burton. 



Highfield, Gainsborough, January 6. 



EAST AFRICA AND ITS BIG GAME} 



■pOR sporting purposes Cape Colony and the adjoining 

 -^ districts are long ago " used up," and the hunter 

 who would fain see "big game" must follow Mr. Selous 

 into Matabeld-Land and Mashoona-Land, if he does not 

 find it better to cross the Zambesi. Even here, some of 

 the largest animals are already exterminated. The re- 

 doubted hunter whose name we have just mentioned 

 has not met with a White Rhinoceros din-ing the past 

 four seasons, and his "bag" of ivory shows a yearly 

 diminution. So much for the south of the Dark Conti- 

 nent. The northern entrance to the great Interior, which 

 afforded Sir Samuel Baker and those who followed him 

 such splendid sport on the Atbara and Settite, has been 

 closed up by the Mahdists, and until we have made up 

 our minds to " clear out Khartoum," no European can hope 

 to penetrate in this direction. There remains, therefore, 

 only the eastern coast as a mode of access to the wild 

 interior of game-tenanted ^Ethiopia, the west coast 

 being practically closed by swamps and fevers. 



On the eastern coast of Africa, however, immediately 

 under the equator, a splendid stretch of high-lying land, 

 full of big game, and easy of access, is still open to the 

 enterprising sportsman. First made known to us by the 

 German missionaries Rebmann and Krapf, the " Kili- 

 manjaro District," as it is now usually called, was sub- 

 sequently opened to us by Von der Decken, New, and 

 Hildebrandt. To these explorers succeeded Mr. Joseph 

 Thomson on his route to Masai-Land, and Mr. H. H. 

 Johnston on his expedition up the Kilimanjaro Mountain, 

 to which Dr. Hans Meyer and other more recent travellers 

 have also devoted their special attention. Access to this 

 sportsman's paradise is rendered easy by the port of 

 Mombas, now under the benign sway of the British 

 Imperial East African Company, and connected with 

 Aden by a regular line of steamboats. Here, in the 

 autumn of 1886, having made the necessary preparations 

 at Zanzibar, the author of the present volume, with his 

 brother sportsmen Sir Robert Harvey and Mr. H. C. V. 

 Hunter, assembled their caravan. Their plan was to 

 reach as quickly as possible the forest of Taveta, distant 

 about 250 miles from the coast and within ten miles of 

 the base of Kilimanjaro, and having established their 

 head-quarters in this favoured spot, to work thence the 

 surrounding plains and open country. Mr. C. B. Harvey, 

 the brother of Sir Robert, was to join them when his leave 

 commenced, a month later. 



How well this programme was carried out the entertain- 

 ing pages of Sir John Willoughby's narrative fully explain 

 to us, while the map at the commencement clearly shows 

 the route and the nature of the different districts traversed, 

 as they appeared to the eyes of the enthusiastic sportsmen. 

 Much time and trouble was saved to the expedition by 

 the selection of a Maltese named Martin as " chief of the 

 staff." Martin had accompanied Mr. Thomson during 

 his adventurous journey into Masai-Land, and was, more- 

 over, the owner of a " freehold building-site " at Taveta. 

 Hereon was a house and a range of huts, forming three 

 sides of a large square, while the fourth was bounded by 

 a sparkling rivulet well stocked with fish. Such a haven 

 of refuge, protected, as it was, by a thorn-hedge with a 

 strong gateway, and situated in the immediate vicinity of 

 a good game-country at an elevation of 2400 feet above 

 the sea-level, seemed little less than a Paradise to our 

 travellers, who arrived here on December 26, about six- 

 teen days after leaving Mombas. Into their various ex- 

 cursions from this convenient centre we need not closely 

 follow them. Suffice it to say that their routes were 



' " East Africa and its Big Game, the Narrative of a Sporting Trip from 

 Zanzibar to the Borders of the Masai." By Captain Sir JohnC. Willoughby, 

 Bart., Royal Horse Guards. With Postscript by Sir Robert G. Harvey, 

 Bart. Illustrated by G. D. Giles and Mrs. Gordon Blake; those of the 

 latter from photographs taken by the Author. (London : Longmans, 

 1889.) 



