5o6 



NATURE 



[Sept. 5, 187S 



vinced him that the parallax was certainly less than one second, 

 and most probably did not exceed half a second. It would 

 therefore be understood that the results were purely negative so 

 far as the immediate object in view was concerned, as they did 

 not suggest the existence of any parallax worth following up. 

 The principle upon which the reconnoitring observations were 

 conducted was this : — The effect of annual parallax upon a star 

 was to make the apparent place of the star describe a minute 

 ellipse, of which the mean place of the star occupied the centre. 

 The star was observed twice. At the first observation the star 

 was at or near one of the extremities of the major axis of the 

 ellipse ; at the second observation it was at the other extremity 

 — so that the observations were so arranged that in each case 

 parallax would have the greatest effect it was capable of pro- 

 ducing. 



Lord Rosse gave a Descriptiott 0/ an Equatorial Motmling for 

 a Three-Foot Reflector. — The optical arrangements of the tele- 

 scope recently erected at Parsonstown was exactly similar to that 

 of previous telescopes, and it was only the mounting which was 

 different. The wooden tube, however, which was formerly 

 formed of staves, had been replaced by an iron tube, which was 

 constructed after designs by Mr. Bindon Stoney. The leading 

 peculiarities of the mounting were that the points of reversal were 

 situated at the east and west instead of at the north and south. 

 The bearings on which the instrument turned in right ascension 

 were smaller than in the ordinary mountings. The motions in 

 declination and in right ascension were effected bymeaus of screws, 

 so that on a windy night the instrument could not run away with 

 the observer. The tube was square ; the clock was connected 

 with a strap, and the counterpoise was less than usual. The 

 cage for the observer was independent of the mounting, moving 

 on a circular rail, and with a second motion like that of a derrick 

 crane. The only reflector of a similar size mounted equatorially 

 was that constructed by Mr. Grubb for the Melbourne Government. 

 Lord Rosse illustrated his explanation by means of models of 

 his own and of the Melbourne reflector. 



On the Stanhope *' Demonstrator" or Logical Machine, by R. 

 Harley, F.R.S. — Towards the close of the last century a logical 

 instrument was constructed by Charles, third Earl of Stanhope. 

 The present Earl found the instrument and some fragmentary 

 papers on logic among the relics of his ancestor, and at the sug- 

 gestion of Mr. Spottiswoode, placed them in the hands of Mr. 

 Harley, who has made a careful study of them. Earl Stanhope 

 (born 1753, died 1816) is known to science chiefly by his printing 

 press, microscopic lens, arithmetical machine, the monochord, 

 and steamboat. Eut of his logical speculations, which occupied 

 his thoughts for thirty years, and of his curious contrivance for 

 working logical problems, called by him the demonstrator, 

 nothing has been known. The author did not attempt to give a 

 complete or systematic exposition of the Earl's logical system ; 

 but he brought out those points which serve to illustrate the 

 demonstrator as a means of performing logical inference. He 

 noticed that Stanhope anticipated George Bentham, Sir W. 

 Hamilton, George Boole, and others in the quantification of the 

 predicate, and notably De Morgan's rule for the numerically 

 definite syllo;]fism. Stanhope states the rule as applicable to all 

 syllogistic reasoning, and he constructed his demonstrator for the 

 mechanical working of this rule. 



On Edmunds' Electrical Phonoscope, by W. Ladd. — This is 

 an instrument for producing figures of light from vibrations of 

 sound. It consists essentially of three parts — an induction coil, 

 an interrupter, and a rotary vacuum tube. 



The action of the instrument is as follows : — Sounds from the 

 voice or other sources produce vibrations on the diaphragm of 

 the interrupter, which, being in the primary circuit of the induc- 

 tion coil, induce at each interruption a current in the secondary 

 coil, similar to the action of a contact breaker, or rheotome ; 

 therefore each vibration is made visible as a flash in the vacuum 

 tube. 



The tube revolving all the time at a constant speed, the flashes 

 produce a symmetrical figure, as the spokes of a wheel, as in the 

 Gassiot's star. 



The number of spokes or radii are according to the number of 

 vibrations in the interrupter during a revolution of the tube, and 

 the number of vibrations being vaiied to any extent according to 

 the sounds produced, the figures in the revolving tube will be 

 varied accordingly. 



Tlie same sounds always produce the same figures, providing 

 the revolutions be constant. In case of rhythmical interruptions 

 being produced in a given sound, as in a trill, most beautiful 



effects are noticeable, owing to the omission of certain radii in 

 regular positions in the figure. 



The uses of this instrument are the rendering visible of sounds 

 and showing the vibrations required in their production, and is a 

 mode of confirming by sight an appeal to the ear. 



The phonoscope is the invention of Mr. Edmunds, part- 

 ner in the firm of Ladd and Co,, London, by whom it is 

 manufactured. 



On Byrne's Battery, by W. Ladd. — This is the invention of 

 Dr. Byrne, of Brooklyn, U.S.A. — The chief features in this 

 battery are a compound negative plate and a simple mechanical 

 means for preventing polarisation. 



The negative plate consists of the extreme negative element* 

 platinum, backed up by a plate of copper to reduce the resist- 

 ance, the copper being protected by a thin sheet of lead to pre- 

 vent any local action that might occur owing to holes in the 

 platinum, which might allow the exciting fluid to attack the 

 copper, and a thicker sheet of lead on the back of the copper, 

 which is japanned ; so a plate in section would show as consist- 

 ing of, first, a sheet of platinum, then thin lead, then copper, 

 and last by the thick japanned lead, the whole being soldered 

 together to form a solid plate. The batteries are built up with 

 a zinc plate and two of the compound plates, the exciting fluid 

 being a bichromate of potash and dilute sulphuric acid solution. 



This battery would soon become polarised but for the injection 

 of air between the plates, which action appears simply mechanical 

 and not chemical, various gases producing no different effects. 



When the air is pumped in the most extraordinary effects may 

 be produced, the quantity being enormous, being more than 

 double that of any other battery of the same size. It is much 

 used in the States for surgical operations, its extreme portability 

 and control rendering it peculiarly useful in this direction. The 

 platinum loop can be raised to any temperature and kept at the 

 same simply by the action of the foot on the bellows, leaving 

 both hands at liberty for operating, there also being an entire 

 absence of fumes or other disagreeable smells. 



A battery of four small cells will heat nine inches of No. 16 

 platinum wire to redness. 



There is also another form of this battery in which the plati- 

 num is platinised : the exciting solution is composed of one part 

 sulphuric acid to ten of water. In this form no air is required 

 to be pumped through the solution. This is used as a motor 

 battery for driving sewing-machines. The inventor states he 

 has driven a heavy Singer sewing-machine for eight hom-s a day 

 at a cost of twopence, including everything. As yet nothing 

 has been done in this direction in England. 



Dr. Janssen gave an account of his method of solar photo- 

 graphy, and exhibited some beautiful photographs of the sun, 

 and Mr. G. J. Stoney explained his spectroscope of very large 

 aperture. Mr. J. R, Wigham explained the quadriform group 

 flashing gas light, as used at Galley Head Lighthouse, with 

 illustrations, and also a gas gun, which might be fixed on a rock 

 in the sea at a considerable distance from a lighthouse or a fog- 

 signal station, and fired as often as required from the station, 

 without the keeper leaving his post : a gas gun was placed in the 

 college grounds, and was several times fired from the table of 

 the room in which the section met. Prof. Haughton gave an 

 account of his investigations on the sun heat received at the 

 several latitudes of the earth, taking account of the absorption 

 of heat by the atmosphere, and of his conclusions therefrom with 

 regard to geological time. 



The section was divided into t^-o departments on the Monday 

 and Tuesday. There were twenty -two mathematical commu- 

 nications which were read in the department of mathematics, 

 including papers by Mr. Spottiswoode On the Eighteen Off- 

 er dinate° of a Conic in Space; by Prof. H. J. S. Smith, On the 

 Modular Curves ; hy Prof. R. S. Ball, On the Principal Screws 

 of Inertia of a Free or Constrained Rigid Body; by H. M. 

 Jeffery, On Cubic Curves; by Mr. J. W. L. Glaisher, On Certain 

 Special Eftumeraiions of Primes, and On Circulating Decimals ; 

 by Mr. F. Purser, On the Geometrical Treatmettt of Bi-circular 

 Quartics ; and by Dr. Hirst On Halphen's N'ezv Form ofChasles s 

 Theorem on Systems of Conies satisfying Four Conditions. 



SECTION C— Geology, 



On the Influence of Strike on the Physical Features of Ireland, 

 by Edward T. Hardman, F.C.S., Geological Survey of Ireland. 

 — Althou£rh not often mentioned in geological works, the in- 



