G54 



TKLF.SCOPF.3. 



and left flashes corresponding; with the Juts and d.ishes 

 lit' llii- ordinary telegraph ulpluilx-t. In Stern s system, 

 which is now used by the French cable, having iih 

 tcrminiM at North I'Listham. Mass . tin- light i> H.i>hcd 

 by reflection from an extremely light mirror, which i.-. 

 turned to right and li'ti by tin: opposing influence of 

 jMisiiivc and negative impulses. 'I his system h.i- the 

 adt anugc of bciiu' operated willi very .slight impulses, 

 but also the AMTUltUB "I leaving im permanent 

 re.iir 1 To seeuro the latter very important end. tho 

 recording instrument li.is been ailo|>teil. The recorder 

 is a horseshoe magnet, electrified by the usual circle 

 of fine win.-, and attracting a small metallic coil. The 

 coil is hung between the HMfMt-pobl : an<l by :i light 

 lever and a thread almost as fine as the str.ind of a 

 cobweb it U connected with a deli. vile siphon hung in 

 a little reservoir of ink. The ink is, electrified, so na 

 to produce a repulsion of the particles, making it flow 

 more readily through the siphon, which outside is about 

 the Hie of a darning-needle, and the interior lul>e 

 !y larger than a hair. The lower end of I lie 

 siphon rests against a paper tape playm; perpendicu- 

 larly through rollers. J'hc whole machine is almost 

 of gossamer fineness and flexibility, so as to minimize 

 the electric strain necos.iry for working the cable. The 

 Com mercial (or Mackay- Bennett) Company has adopted 

 the sy.-tem known as the William Thomson siphon 

 recorder. Betwci n the two poles of a powerful magnet 

 is suspended a piece of soft iron. In this the mag- 

 netism is concentrated. In the field is suspended a 

 coil of fine wire. The motion of the coil is transmitted 

 to the siphon fed with the purest aniline ink by 

 means of a silk fibre so fine as to be almost invisible. 

 A revolving elect lie motor feeds the ink generator by 

 induction between its armatures and two enveloping 

 shields, and that induces the current The instrument 

 used in Wall street, New York, is very small and the 

 work noiseless. An endless tape passes under the point 

 of the siphon, which moves back and forth at the rate 

 of 100 dots a second. The tape can be read at any 

 time, and the messages preserved ; but this could not 

 be done by the old system of mirrors. 



It has been proposed to establish telegraphic com- 

 munication between Australia, New Zealand, Canada. 

 andtircat Britain, by means of a line perfectly imle 

 pendent of existing lines and freed from foreign influ- 

 ences. This would rctjnire a chain of cables ar:ss tlir 

 Pacific' Ocean from Brisbane or Sidney to the north of 

 New Zealand, thence via the Fiji Islands, the Fanning 

 Klands. the Sandwich Islands to Vancouver Island, 

 then across to the new city of Vancouver on the main- 

 land, the terminus of the Canadian Pacific Hallway. 

 The line would follow this railway and be extended 



possibly to Gaspe. in the Province of Quebec. I i 



Gaspe a new cable would be laid through the Straits 

 ic Isle to l!ic United Kingdom, unless it was 

 found to l>e practicable to secure control of the existing 

 lines across the Atlantic. The total length of cables 

 contemplated in the Pacific and Atlantic Oceans is 

 11.14.') miles, and the distance aero.- ihr continent 

 will be :;4.~>0 miles, making in all about 15.000 miles. 



Since the opcniiiL' of the first Atlantic cable the 

 rated charge'] for the messages have been steadily re- 

 duced, as is shown by the following : In 1S60, $100 

 were pliarucil for 20 words or loss; from November, 

 1867. $:.o for 20 words or less: from December, lsf.7. 

 *-'.'. for 10 words or less ; from September, 1808, $10:85 

 ior 10 words or less ; from June. 1869, $10 for 10 words 

 or km ; from AULMISI. |sr,9. $7.50 for lOwords or 1< -s ; 

 from December, INTO. $15 for 10 words or less; from 

 July. 1.HT1. $1(1 for 10 words or less; from May. ]X7'J. 

 $1 JK.T word ; from May, lS7. r >, 50 cents per word ; from 

 I!M r lv| to cents per word. (K. (i. M.) 



TKLK8COPE8, AMKIIICAN. The earliest mann 

 f.ietnrer of astronomical telescope-, in tin- I'nitcd Stales 

 of whom we have record was Amasa Holcomb. of 

 Sonthwick. Mais. He made his first experiments in 

 grinding lenses in 1826, and completed in 1830 an 



achromatic objective of about 48 inches focal length. 

 1 win ""''"" however, to the difficulty of 'ob- 



<f U ifcl ta '"'"'- "".''' *i lll> 



Vm Kep.).' turned his attention to the manu- 



facture of reflecting telcsco|>e8, and 

 achieved considerable smvcss in this direction. His 

 r. tie. tors were from 4 to 10 inches in diameter, 

 m> iiiiied in the llersehelian form ; that is. with the 

 mirror inclined slightly to the axis of the t 

 that the ima:;e is formed near the upper edge of the 

 lube, and is there magnified and ex.imincd. In 1838 

 Mason. Smith, and Bradley, the tw. first, at that time, 

 -In di i;ts in Vale College, built a reflector of Ili indie* 

 aperture, with which some very creditable work upon 

 nebula' was accomplished. 



Thirty years ago the most prominent telescope- 

 inaker in the 1'nited States was Mr. Henry Fitz, of 

 New York. His largest objectives are given in the 

 table below. Spencer, of Canastota. N. V.. made in 

 IS.V. the l.'ij-in. refractor of the Litchticld Observa- 

 tory of Hamilton College, with which Dr. Peters has 

 red no less than 47 asteroids, and I 'avis, of 

 Cincinnati, an 1 1 -in. objective which is now mounted at 

 Smith College, Northampton. Mass. Many small ob- 

 jectives, some of a very high order of excellence, have 

 been produced by American opticians Stendicke. 

 Kahler. (Jivgg. Allen. V-'alther. Byrne. Claccy. and 

 Tolles. the three last-named making especial efforts to 

 (.rind lenses of short focus. Clacey's largest glass, of 

 IdJ in. aperture and '.I ft. 9 in. focal length, has re- 

 cently been completed for the Smith Observatory, 

 (icneva. N. V. The ratio of aperture to focal length 

 is here 1 to 12, while the usually accepted ratio is 

 about I to l">. 



Kefleeting telescopes have thus far met with com- 

 paratively little favor in this country. The only one 

 of large size (2.H in.) was made by I>r. Henry Draper 

 in lsiii'i-70, and used by him at his observatory nt 

 Hastings on the Hudson in researches in spectrum 

 photography. This instrument was removed in l.sST 

 to Harvard College ( >bservatory, where it is now used 

 for similar work under the direction of Prof. Picker- 

 ing. Brooks, formerly of 1 'helps, N. Y., has made 

 two reflectors, of 9 and II in. respectively, with 

 which he has been remarkably successful in searching 

 for comets, discovering 13 comets within 6 years. 

 Brashear, of Allegheny, has made a number of very 

 excellent rcflectoi-s with silvered -ulass mirrors, ranging 

 from 5 to 15 in. in diameter, lie has also consinu ted 

 several small refractors, and is now at work upon a 

 Iti-in. objective with "photographic I-OITCI -tins.' lens" 

 for Carlton College Observatory. Dr. ('. S. Hastings 

 has figured several excellent objectives upon theoret- 

 ical curves; his largest, of '.'. 4 in. aperture and re- 

 markably perfect, i.s mounted at the .Johns Hopkins 

 University. 



Alvan Clark ((]. r.). who has become famous as 

 an optician the world over, began his career as a tel- 

 escope-maker in fslii. In ISliO he finished a telescope 

 of 18} in. aperture, then the largest refractor known. 

 In testing it Mr. Alvan <i. Clark discovered the com- 

 panion of Sirius. the existence of which had long been 

 indicated by theory, though it had hitherto escaped 

 detection. This first of the great Clark refractors was 

 originally intended for the University of Mississippi, 

 but. being prevented by the civil war from reaching 

 ii- destination, it was purchased by the Chicago As- 

 tronomical Society and mounted at the Dearborn ()b- 

 -rvatory. In 1ST:; the Clark'' completed a I.V. in. 

 refractor for the I' S. Naval ( )bscrvalory at Washing- 

 Ion, the contract price for whi'-h was Sir,. mil ; and. at 

 iln Mime time, tlicy made for Mr. lycandcr McCor- 

 mick an objective of a slightly larirer aperture, which 

 they mounted in Iss:! at the I'niver.-itv of Virginia. 

 With (he former instrument Prof A Hall dis- 

 in IS77 the two small satellites of Mars. In I.S79 tho 

 Clarks entered into a contract with the Russian gov- 

 ernment to furnish an objective of 30 in., and in 1880 



