Aug. 11, U8-\] 



KNOWLEDGE 



187 



degree that 5-2&tli9 are less than 13-llth or 2G-28ths. It is thus 

 less than a fifth of what it had been at the earth's surface. — \V. 

 Cave Thomas. Many thanks for abridgment. It relieves from 

 a ditficulty. — .Sqi'ikt irill bo much obliged by any information about 

 table fountains. — E. H. Pressure varies directly as the height 

 of the barometer. — W. SouTH.HL. A botanical account, by a 

 botanical writer, shortly. — J. C. L. The peculiarity you notice is 

 due to alienation. So far as precession is concerned, the R.A. of 

 Sirius is steadily increasing throughout the year by about 2^ sec. ; 

 but as, owing to aberration, Sirius appears to move in a small 

 ellipse, whoso [major axis is 40J" or 2§ sec. in length, the steady 

 increase due to precession is converted into an apparent alternate 

 increase and diminution, the increase being the greater. — Lux. The 

 cause of the earth's tilt is unkno^vn ; but it cannot be that you 

 suggest. If any terrestrial cause were to carry the seas to the 

 northern hemisphere, the tilt would not be appreciably altered. — 

 S. P. A slip for Israel, no doubt. — J. E. Beodie sends us accounts 

 of the Gas-light and Coke Company showing that the residual pro- 

 ducts, including coke, do not amount (as Mr. W. M. Williams said 

 in his article on Electromania) to half the cost of the manufacture 

 of gas, and in Bristol not to 40 per cent. 



ELECTRICAL. 

 J. H. Ward. — 1. Be careful to well soften the iron wire. 2. 

 Three layers of No. 18 or 20 cotton, covered and paraffined, will 

 suiEce for the primary coil. 3. The secondary coil sliould be well 

 insulated from the primary by several layers of paraffined paper. 

 You may use No. 36 or 38 wire, but it should be silk-covered. It 

 is no economy to use cotton-covered wire, because the insulation 

 necessary to compensate for the poorness of its insulating proper- 

 ties more than neutralises this or any other counter advantage. 

 The length of the secondary wire will depend upon the kind of 

 spark you require. If you want a short, thick spark, make a 

 comparatively short, thick coil, but if you desire a long, sharp 

 spark, then the length of your coil must be greater in proportion to 

 its diameter. A verj' convenient proportion is to make the total 

 diameter about one-third of the length. 4. The paper you send is 

 not the best ; you will find it better to use ono layer of paraffined 

 foreign note pajier ! with silk-covered wire this will be quite suffi- 

 cient. Have you determined to make your coil of uniform thick- 

 ness from end to end ? 



THE TELESCOPE. 

 Geo. Harbison. You are quite right about S Herculis. Culpa 

 iirstra. On the very day on which your queries were received we 

 had been writing a description of another star, and, in a manner 

 absolutely inexplicable to us, seem to have repeated part of such 

 description in our reply to yourself. The comes is really, as you 

 say, nearly vertically over the larger star. Our statement that the 

 position angle has only varied some 22° during the last eighty-two 

 years is, however, strictly correct. — J. N. Colley. You have got 

 hold of one of the old Gregorian telescopes, with metal reflectors. 

 The loss of light in this form of instrument is very serious indeed, 

 as it has to undergo double reflection (with its consequent great 

 absorption), besides its transmission through the eyepiece. This 

 may, possibly, be aggravated, in the case of your own acquisition, by 

 the dirtiness of the mirrors. If they are clouded or speckled, you 

 may buy a little citric acid and water and a very soft wash-leather 

 as a means of removing impurities ; but, wo must repeat, the funda- 

 mental principle of the instrument itself must always cause a serious 

 loss of light. — Comet. You do not oven now furnish the informa- 

 tion whether your telescope is mounted (so to speak) at the top of 

 the polar axis, or on ono side of it. If the former, you must, per- 

 force, turn the instrument round to reach the pole, as you can never 

 place your telescope parallel with the polar axis. You had better 

 buy Noa. 386 and 389 of the Einjlish Mechanic for tho rudimentary 

 information you appear to require. 



Dr. STANFOun E. Chaille, a prominent New Orleans physician, 

 has published an article in a medical journal to show the effect of 

 the Mississippi floods on tho health of tho city, lie presents tho 

 mortality statistics of twelve overflows, including in each case tho 

 deaths for tho year, and for tho preceding year, aiul for the follow- 

 ing one. After a careful examination of tho history, facta, and 

 opinions, ho concludes that these "fail to indicate that tho partial 

 inundations of New Orleans have ever inlluonced unfavourably its 

 mortality, whether by yellow fever, by cholera, by malarial fevers, 

 or by diseases generally. On tho contrary, tho evidence, though 

 imperfect and not fully conclusive, justifies tho inference that tho 

 deposit and decomposition of filth, and any other pron.oters of 

 disease which may be duo directly to inundations, are more than 

 counterbalanced by tho flood, which first covers up tho soil, from 

 whence springs so much disease, and then helps to clcanso it.'' 



Science anil 9it (8o£(gip. 



SiN-CE the hot season began, sixty-four ship captains have died of 

 yellow fever at the different Cuban ports. 



The Census Bureau of Japan reports for 1881 nearly 900,000 

 births and about 600,000 deaths. 



The latest enumeration of Japan's military forces show 43,700 

 men in the standing army, including the Imperial Guard, and 58,000 

 Reserves. 



An inexhaustible mine of corundum stone, tho next hardest known 

 substance to the diamond, has been discovered in Butts County, Ga. 

 It resembles the sapphire, is susceptible of high polish, and is 

 valuable in many ways. 



Cholera increases s1ia\1\ in n i il iul, Tokio and Yokohama, 

 Japan. Its ravages are m lo poorer classes, several 



high officials having bii ;, The daughter of Prince 



Arisugaua, the Emperor's mi ;>■, li. i :,rti r a brief illness. 



Swans on the Thames. — The officials of tho Croivn and Dyers' 

 and Vintners' Companies have just completed tho numbering and 

 nicking of the swans on the Thames between Southwark-bridge 

 and Henley. There are now upwards of 400 old birds and cygnets 

 on the upper reaches of the river, nearly 300 of which are tho pro- 

 perty of the Crown, the remainder being owned by the Vintners' 

 and Dj-ers' Companies. 



Tea Cultivation in New Zealand. — Some time since the Accli- 

 matisation Society of New Zealand invited Mr. Rcid, a gentleman 

 connected with the cultivation of tea in India, to make experiments 

 with tea-plants grown in the gardens of the society at Auckland. 

 Mr. Reid did so, and has lately made his report, which is eminently 

 satisfactory, and shows that the plant can be most successfully cul- 

 tivated in that district. 



Mr. Proctor's LECTrnES ox Astronomy. — In reply to several 

 questions, the Editor begs to state that he has agreed to deliver at 

 several places, during the forthcoming lecture season, lectures 

 selected from the following list : — 1. Birth and Growth of Worlds ; 

 2. Life and Death of Worids ; 3. The Sun ; 4. The Earth-Uke 

 Planets ; 5. The Giant Planets ; 0. The Moon ; 7. Comets and 

 Meteors ; 8. Tho Star Depths; 9. The Transits of Venus; 10. The 

 Giant Pyramids. All of these can be illustrated with the oxy- 

 hydrogen lantern (where procurable) from Mr. Proctor's collection 

 of more than a thousand photographic slides. The first seven 

 (only) can be illustrated by means of paintings on canvas. 



Saving Life. — In consequence of the numerous fatal accidents 

 brought under the notice of the Royal Humane Society by tho 

 want of the knowledge of swimming, tho committee have resolved 

 to grant a silver medal annually to many of the leading public 

 schools for proficiency in the art with a view to saving life. Rules 

 have been drawn up for the guidance of the head-masters who 

 have signilied their cordial approval of the scheme. It is not con- 

 t. II ; ' ! I i> make the medal a personal decoration, as it is con- 

 i ! I i 111 would tend to depi-eciato the medals of tho society 



1 . ; \ iiig life from drowning at personal risk. The rules 



.si.UL :u I ii\ t L tliat a medal will be awarded to each selected school, 

 the competition to bo open to all the boys, subject to the approval 

 of the head-master, and to take place in 'the river or bathing-place 

 used by tho school, and to be carried out under the supervision of 

 tho head-master, or such umpire as he may appoint. Each boy to 

 have one trial under certain specified conditions. Tho medal and 

 its accompanying testimonial inscribed on vellum is to be awarded 

 to the boy who obtains the greatest number of marks in tho trials. 



A Srrpo.sEi) Mkteor.— Mr. N. S. Drayton, of Jersey City, writes 

 as follows to the editor of tho Scientijic .'liiit'nVan ;— " On the 

 tho evening of the 0th, while engaged iu ' sweeping ' tho vicinity 

 of Ursa Minor tor double stars, my attention was drawn to a bright 

 object about the size of a star of the second magnitude moving 

 slowly from west to east. It passed within a degree of Polaris 

 and continued steadily on its course eastward, disappearing from 

 view in the neighbourhood of Capriconuis. Tn colour this object, 

 a meteor, doubtless, was deep red, without scintillations or train of 

 any kind, and its slow movement wos in marked contrast with tho 

 rapid flashing of tho common ' shooting star.' It was visible to 

 mo fully three-fourths of a minute, varying but slightly in bright- 

 ness during that time. In tho closeness of my attention to its 

 movement I neglected to note tho time of its appearance, but 

 judge it to have been near half-past ten. Perhaps there were 

 other of your readers who observed tho phenomenon, and can add 

 more specifically to my testimonv."— N. S. Dba\-ton— Jersey City 

 Heights, July 8, 1382. 



