Dec. 22, 1882.1 



• KNOWLEDGE 



483 



paint is vastly on the increase, and its future will doubtless 

 be very great. Not only is it used by Government, as during 

 this last Egyptian war, but also by several railway com- 

 panies, as an experiment for lighting their carriages through 

 tunnels, and by many private individuals, for buoying chan- 

 nels at night, and a variety of similar purposes. An ex- 

 ample of this is the painting of the end of Folkestone Pier, 

 to act as a beacon at sea. 



When we appreciate the number of lives that may 

 annually be saved by this and other practical applications 

 of scientific facts, the truth is most forcibly brought home 

 to us that " knowledge is power." 



THE AURORyE. 



IN justice to these interesting phenomena, it is only right 

 to remark that the one of the 1 7th was only a part of 

 a series extending from the 13th to the 24th, at least, and 

 that during this period sun-spot and magnetic disturbances 

 were correspondingly active. 



The sun-spot you have figured (p. 431), as sketched at 

 11 a.m., November 20, had much changed in detail by 

 10 a.m. the next day, and it would fill pages to notice the 

 almost wouderfvil needle variations and solar storms which 

 have accompanied the recent auroral displays. With 

 reference to the still enigmatical spectrum of the aurora, 

 will you permit me to record that the moving patch of 

 light seen at 6.10 on the 17th was really an auroral cloud 

 or beam, and not a meteor, as described in the Times. 

 With the spectroscope I found only the auroral citron line, 

 and none other. [Correspondents who are calculating orbit 

 of supposed meteor, please note. — R. P.] 



The moonlight gave no opportunity to examine the full 

 spectrum ; but I should like to ask your spectroscopic 

 readers (as we are now at an auroral epoch) to direct their 

 particular attention to the fainter lines towards the violet 

 (the red and citron are already closely positioned) of this 

 spectrum. It must not, however, be expected to measure 

 these except in a dark field, and a companion .spectrum or 

 illuminated scale would render them invisible. A single 

 illuminated line or point, a dark diaphragm traversing the 

 field, or a photographed transparent micrometer illuminated 

 by the spectrum itself, will alone give hope of success. 

 Touching the hnniere cendree on the moon, described by 

 one of your correspondents, as seen during the aurora, I 

 also remarked this, but found it pink in tint, instead of 

 green. T. Rand Cai'hon. 



THE TRYPOGRAPH. 



EVERYONE who has used stencil plates must have often 

 thought how convenient it would lie to extend the 

 system. But even in single letters the method fails ; you 

 cannot stencil an O, or a P, or an R, a D, or a 15 ; at 

 least, you have to complete the letter afterwards. To 

 stencil ordinary writing, and still more, a drawing, seems 

 hopeless. Yet this is what the " Trypograph, or Hole- 

 Writer" does. The idea is a good one, and simple in the 

 extreme, — when sJiovn : (like Columbus's trick with that 

 weary egg which we all wish had never been laid). You 

 write or draw %\ith a metal pencil on stencil-paper — that 

 is, paper specially ju-epared to suit the work — placed on a 

 metal plate the surface of which is like that of a finely 

 cross-grained file. As the pencil presses the paper 

 against this surface, multitudes of minute holes are made 

 along the pencil's track. Then the stencil-paper is ready 

 for use any number of times, precisely as a stencil-plate is 



used. A broad, fiat scraper, dipped in a certain kind oi 

 ink, is passed over the paper, and the ink, passing through 

 the holes, duly marks a sheet of ordinary paper underneath. 

 Any number of copies may be taken in this way, each re- 

 quiring only a single stroke of the scraper — at least, after 

 a little practice has been obtained. A most convenient 

 instrument this, where writing or drawing has to be many 

 times copied ; cheap, too, and easily used, success being 

 readily attained at a first or second trial, and thereafter 

 systematically. 



The New York Edison Company state that they are 

 now lighting from their central station in Pearl-street, 191 

 houses, with 4,288 lamps, of which over 2,700 burn almost 

 continuously. It is expected that an additional 1 ,000 lamps 

 will be in use before the end of the year. The fire in- 

 surance companies make no difiiculty about granting 

 licences. 



The Ferrasti Dynamo Machine. — This machine, which 

 is a combination of the invention of Sir W. Thomson and 

 M. Ferranti, has for some weeks been causing a consider- 

 able commotion in the electrical and stock-broking worlds. 

 It is at length made public, and bids fair to far outstrip 

 anything yet produced for incandescent lighting. All the 

 details are not yet available, but it is our purpose to supply 

 them when the proprietors consider their patents secure, 

 which they tell us will be about four or five weeks hence. 



The Advantage op Knowino how to Swim. — The 

 Sydney Morning Herald of August 25 says : " We learn 

 from a correspondent that, a short time ago, ISIrs. G. A D. 

 McArthur Campbell, formerly a resident of Coonamble, 

 distinguished herself by a deed of admirable bravery. Mrs. 

 Campbell was a passenger in a steamer from Hong Kong to 

 one of the northern ports of Queensland, and one day a 

 little boy about four years of age, to whom the lady ^yas 

 much attached, fell overboard, the accident occurring 

 through a sudden lurch of the vessel. With the exception 

 of Mrs. Campbell and the man at the wheel, all the pas- 

 sengers and crew were at dinner. Without waiting for a 

 life-buoy, or divesting herself of any clothing, and simply 

 saying to the man at the wheel, " Don't tell the child's 

 mothei-," Mrs. Campbell plunged into the water, swam to 

 the boy, and held him up till both were rescued, the 

 steamer having been promptly stopped and a lioat loweretl. 

 Neither the lady nor the boy was much the worse for the 

 immersion." 



A Whale Snaps a Log-Line. — A correspondent sends 

 the following : — " On the writer's last voyage from Balti- 

 more to Rio de Janeiro, riA Pernambuco, his attention was 

 called to a large whale leisurely fioating on the water near 

 the stern of the vessel. All at once he seemed possessed 

 with a spirit of frolic, diving and coming to the surface 

 with the most playful motions. As his huge head 

 descended, he would slowly expose his tail, until for 

 several seconds it remained erect on the water. I chanced 

 to have one of Messrs. John Bliss it Co.'s logs in use, the 

 line and rotator towing astern. Never in thirty years' of 

 sea experience did I see or hear of a whale biting anything, 

 but, to my surprise, he took the rotator of that log in his 

 mouth, immediately my mate and a passenger, in order 

 to save the indicator, seized the line, which quickly 

 snapped in their hands, and was drawn oil' by the whale, 

 who wound it round and round his head until he appeared 

 completely Ixnvildered. This incident occurred in lat. 

 lO'' ;")' south, long. 38^ 11' west. I would advise all ship 

 masters to haul in their line and rotator when whales are 

 about, or they may lose them as did your obedient servant, 

 John T. Holt, master of ship David Stewart." 



