2 4 



NATURE 



\7an. 24, 1878 



Y^th of an inch the focal length of the convex and concave 

 surfaces under operation. 



Although I have heretofore described the cellular casting as 

 having a flat face, it will be obvious that if made into a concave 

 corresponding with the intended focal length of the reflector that 

 much thinner sheets of glass than those before named may be 

 employed by first bending them to the required curve and fitting 

 them by grinding to the concave iron surface, so that a glass 

 reflector can on this principle be made just as large as a plate- 

 glass manufacturer can produce an ordinary thin plate. 



A description of the novel arrangements which I employ for 

 grinding and polishing the spherical concave reflector, and its 

 conversion into a paraboloid of revolution would carry me far 

 beyond the already too lengthy remarks I have made, and which 

 had for their primary object simply to show that we may still 

 have good reason to hope that silver- on-glass reflectors of large 

 diameters are within our reach. Henry Bessemer 



Denmark Hill, January 21 



A Telephone Without Magnetism 



For some time past I have been experimenting with the view 

 of transmitting articulate sounds through wires without the aid 

 of electricity or magnetism. 



I have now been quite successful, my experiments proving that 

 the sounds of the human voice can be carried by vibrations 

 through considerable lengths of wire. 



Last night conversation was carried on with ease between four 

 individuals, situated in different rooms. Piano music, singing, 

 laughing, and breathing, were all clearly transmitted to the ear. 



The whole distance would be about fifty yards. 



The communication was effected by means of a mouth-piece 

 with a vibrating disc in connection with the wire. 



Glasgow W. J. Millar 



Change of Habits in Toads 



While prosecuting my field-work as Paleontologist of the 

 United States Geological Survey of the Territories, under the 

 direction of Prof. F. V. Hayden, in Colorado, during last season, 

 I had the opportunity to make some very interesting observations 

 in relation to a change of habits in the common toad {Bufo ame- 

 ricana). The district referred to is that portion of the great 

 plains which lies immediately adjacent to the eastern base of the 

 Rocky Mountains, and which is traversed by the South Platte 

 River and its tributaries there. 



The valleys of these streams are broad and shallow, and the 

 streams heading in the immediately adjacent mountains have an 

 abundant flow of water ; so that large tracts of land in all those 

 valleys have been brought under cultivation by irrigation. Irri • 

 gation is necessary in all that region, for it lies within that por- 

 tion of the United States domain upon which the annual rainfall 

 is insufficient for the purposes of agriculture.- 



With the irrigation of the land cams increased and perennial 

 vegetation ; with that came increased insect-life, and with that 

 an increase of birds and toads. The irrigating ditches are every- 

 where numerous, and during the season of growing crops they 

 are frequently visited by men to regulate the flow of water to the 

 land. 



This and other circumstances disturb the toads that frequent 

 the shades of the herbage which grows upon the borders of the 

 water. It is no uncommon thing for toads as well as frogs, to 

 jump into the water when disturbed, but the habit of the former 

 is to make a shallow dive, rise immediately to the surface, and 

 swim upon it by a sweeping curve to the shore again, not resting 

 until the brink is gained, upon which they tarry a while before 

 coming upon the land. 



Frogs, on the contrary, when disturbed, make a strong dive 

 directly to the bottom, upon which they lie prone, with the legs 

 flexed against the body, and into the mud of which they settle 

 themselves a little. Here they remain and exhaust the patience 

 of one who may attempt to wait for them to rise. Now the 

 toads in this irrigated region have adoptedprecisely these common 

 habits of the frogs when disturbed upon the borders of the 

 ditches, as I repeatedly witnessed. I regard this as the resump- 

 tion of an instinctive trait that has been potentially transmitted 

 from a former race of Anourans that were less differentiated than 

 frogs and toads are now from each other ; and that the lately 

 introduced change of physical conditions in the region has caused 

 the toads to resume habits which the frogs have never abandoned 

 Washington, D.C., January 6 C.A.White 



Talking Photographs 



The article from the Scientific American on i\it phonograph 

 which is quoted in NATURE, vol. xvii. p. 190, concludes as 

 follows: — "It is already possible, by ingenious optical con- 

 trivances, to throw stereoscopic photographs of people on screens 

 in full view of an audience. Add the talking phonograph to 

 counterfeit their voices and it would be difficult to carry the 

 illusion of real presence much further. " 



Ingenious as this suggested combination is, I believe I am in 

 a position to cap it. By combining the phonograph with the 

 kinesigraph I will undertake not only to produce a talking picture 

 of Mr. Gladstone which, with motionless lips and unchanged 

 expression shall positively recite his latest anti-Turkish speech hi 

 his own voice and tone. Not only this, but the life-size photo- 

 graph itself shall move and gesticulate precisely as he did when 

 making the speech, the words and gestures corresponding as in 

 real life. Surely this is an advance upon the conception of the 

 Scientific American ! 



The mode in which I effect this is described in the accom- 

 panying provisional specification, which may be briefly summed 

 up thus : Instantaneous photographs of bodies or groups of 

 bodies in motion are taken at equal short intervals — say quarter 

 or half seconds — the exposure of the plate occupying not more 

 than an eighth of a second. After fixing, the prints from these 

 plates are taken one below another on a long strip or ribbon of 

 paper. The strip is wound from one cylinder to another so as 

 to cause the several photographs to pass before the eye suc- 

 cessively at the same intervals Jof time as those at which they 

 were taken. 



Each picture as it passes the eye is instantaneously lighted up 

 by an electric spark. Thus the picture is made to appear sta- 

 tionary while the people or things in it appear to move as in 

 nature. I need not enter more into detail beyond saying that if 

 the intervals between the presentation of the successive pictures 

 are found to be too short the gaps can be filled up by duplicates 

 or triplicates of each succeeding print. This will not perceptibly 

 alter the general effect. 



I think it will be admitted that by this means a drama acted 

 by daylight or magnesium light may be recorded and reacted on 

 the screen or sheet of a magic lantern, and with the assistance 

 of the phonograph the dialogues may be repeated in the very 

 voices of the actors. 



When this is actually accomplished the photography of colours 

 will alone be wanting to render the representation absolutely 

 complete, and for this we shall not, I trust, have long to wait. 

 Wordsworth Donisthorpe 



Prinze's Park, Liverpool, January 12 



Sun-spots and Terrestrial Magnetism 



I BEG to direct Prof Piazzi Smyth's attention to an article in 

 the Anmiaire dn Bureau des Longitudes for 1878 by M. Faye, 

 entitled " La Meieorologie Cosmique," in which this distinguished 

 astronomer and meteorologist says : — " La periode des taches, 

 portee a i lans-j par M. Wolf n'etant pas egale a celle des varia- 

 tions magnetiques (io^'""45), ces deux phenomenes n'ont aucun 

 rapport entre eux. " It thus appears rather premature to suppose 

 that the sun-spot cycle and the terrestrial magnetic diurnal oscil- 

 lation cycle are intimately connected. A. W. Downing 



Greenwich, January 21 



Great Waterfalls 



In reply to Mr. Guillemard's inquiry in Nature (vol. xvii. 

 p. 221) he will find some account of the Kavari or Cauvery Falls 

 in the " Mysore Gazetteer," recently-compiled under orders of the 

 Indian Government, vol. ii. pp. 271-273 (Bangalore, 1876). A 

 copy is doubtless to be seen at the India Office Library. 



Edinburgh, January 21 W. W. Hunter 



Mechanical Analysis of the Trevelyan Rocker 



Almost every physical cabinet possesses one of Trevelyan'* 

 rockers, and yet it is rare to find one which always works well 

 and gives complete satisfaction. Some two years ago having 

 experienced this difficulty in New York, where I was then 

 Professor of Physics, I requested Mr. Robert Spice, F. C. S. , of 

 230, Bridge Street, Brooklyn, U.S., a very skilful constructor of 

 acoustic instruments, and a thorough physicist, to make for me 

 several of these rockers and ascertain, if possible, the conditions 



