Sept. 22, 1881] 



NATURE 



491 



blackening of the glass by volatilisation of the carbon when too 

 high electric power came to be applied. The durability of the lamp 

 at any particular power mu,>t be tested by mouths' experience 

 before the proper intensity for economy can be determined. 



Oil some Uses of Faure's Acciimulalor in connalion wHh Light- 

 ing by Electricity, by Sir W. Thomson. — The largest use of 

 Faure's accumulator in electric lighting was to albw steam or 

 other motive power and dynamos to work economically all day, 

 or throughout the twenty-four hours where the circumstances 

 were such as to render this economical, and storing up energy to 

 be draw'n upon when the light was required. There was also a 

 very valuable u»e of the accumulator in its application as an 

 adjunct to the dynamo, regulating the light-givin.j current and 

 storing up an irregular surplus in such a manner that stoppage 

 of the engine would not stop the light, but only reduce it slightly, 

 and that there would alw ays be a good residue of two or three 

 hours' supply of full lighlini; power, or a supply for eight or ten 

 hours of light for a diminished mnnber of lamps. He showed 

 an automatic instrument which he had de-igned and constructed 

 to break and make the circuit between the P"aure battery and the 

 d) namo, so as automatically to fulfil the conditions described in 

 the paper. This instrument also guarded the coils of the dynamo 

 from damage, and the accumulator battery from loss, by the 

 current flowing back, if at any moment the electro-motive force 

 of the dynamo flagged so much as to be overpowered by the 

 battery. 



An Analysis of Rdationships, by Dr. A. Macf.ulane. — The 

 paper contained a summary of the notatiun and elementary laws 

 of an analytical method of dealing svith such ques ions as, in the 

 simplest cases, may be dealt w iih graphically by means of the 

 genealogical tree. The subject is a special branch of the algebra 

 of logic, and its development appears to the author to throw 

 much light upon the fundamental principles of that science and 

 to suggest important que-tions as to the relation of mathematical 

 analysis to ordinary languages. The method has been applied 

 to test the "systemsof affinity and consanguinity " of Dr. Morgan 

 of Rochester, New Y. 'rk. 



On a Microscope with Arrangements for Illuminating the Sub- 

 Stage, by E. Crossley. — The author stated that, using a buUseye 

 conden-er, the light from the lamp is thrown into the hollow 

 horizo ital axis of the microscope, and by means of a prism 

 placed in the centre of this axis is reflected forwards in the 

 direction of the axis on which the swinging sub-stage turns. 

 Th • arm of a swinging sub-stage is made in the form of a box, 

 and carries a second prism on the axis, on which it moves so as 

 to intercept the rays of light coming from the first prism, and 

 reflect them in the direction of the arm or box. At the end of 

 the box is a third prism, which throws the rays of light f irward 

 on t'-) the mirror, by means of which they are finally directed to 

 the object on the stage. No change in the position of the 

 microscope on its horizontal axis affects the direction of the 

 light from the lamp, and whatever the position of the swinging 

 sub-stage, whether above or below the stage, the illumination 

 remains c mstant upon the object. The greatest facility is thus 

 given for illuminating the object at any angle, and also seeing 

 which is most suitable. The prisms u-ed are one-inch, and give 

 sufficient light for a one sixteenth-inch object-glass with a Ross 

 B-eyepiece, a suitable condenser being used beneath the stage. 



Observations of Atmospheric Electricity a'. Kew Observatory 

 during 1S80, by G. M. Whipple. — The author having spoken 

 about the work already done, stated that he had devised a modi- 

 fication of Prof. Everett's method, and lad constructed a glass 

 scale by means of which curves could be tabulated with great 

 facdity. They had com nenced tabuUting and discussing the 

 accumulated records, and he was able to state some of the facts 

 derived from the curves for 18S0. Having determined the 

 atmospheric tension for every hour during the year when 

 measurement of the trace was possible, the diurnal, monthly, 

 and annual variations were computed. The months of maximum 

 tension were January and March, and of miniuaum tension 

 August and September. From the year's observations it was 

 found that the laws vary in summer and winter ; for the summer 

 months the tension was greatest with an ea-t wind and lowest 

 with a north wind, whilst in winter the tension was greale-t with 

 north and north-we.st winds and least with south-east winds. 

 From the results obtained it was f jund that light winds had a 

 higher potential than strong winds. This, hjwever, was not 

 well marked in summer, but is almost entirely due to winter 

 observations. 



On Prof Phillips' atnfall Observations made upon York 



Minster, by G. J. Symons, F.R.S. — The author, referring to 

 the experiments established at York Minster, said that three 

 gauges nearly identical in pattern were placed, one in the 

 mureum garden, one on the roof of the museum, and the 

 third on a pole about 9 feet high placed on the centre tower of 

 York Minster. These gauges were measured at various but 

 identical times during the years 1S32-1S35, and the results 

 were :— 



Total rain. Ratio. 



Museum garden 2 inches above ground ... 2181 ... 100 



Museum roof 44 feet ,, I7'39 •■• 80 



Minster tower 213 feet ,, J2'gg ... 60 



Prof. Phillips stated the real amount of the diminution of 

 rain at the ujiper stations depended upon the temperature of 

 the seasins ; the diminution did not vary uniformly as the 

 square root of height, being in winter only as the cube root. 

 Prof. Phillips' experiments soon became known, and Prof. 

 Bache of Philadelphia set up four gauges at the angles of 

 a square tower 162 feet high. His experiments were reported 

 to the British Association in 1838. In 1861 Mr. Stanley 

 Jevons made an important theoretical contribution to this investi- 

 gation ; he pointed out the weakness of the different extant 

 theories, and showed that the phenomena observed were all 

 consistent with the theory that the fall of rain was practically 

 identical at all elevations, an 1 that the observed differences were 

 due to the im;.erfect collection by the gauges ; he also stated 

 that towers, buildings, and even the gau.;e itself, were obstacles 

 to the rain-bearing current of air, and he concluded that less 

 rain would fall on the summit of the obstacle than elsewhere, 

 the sur,)lus being carried forward to the lee side. Similar obser- 

 vation- have been mnde during the last fifteen years, which have 

 also been sup;ilemeuted by anemometric observations, and these 

 have proved that the difference in the amount collected was 

 always greatest when the wind was stronget. The subject of 

 late has been investigated by Mr. Dine--, whr) placed several 

 gauges 50 feet froji the ground on the tower of his house. In 

 1877 Mr. Dines read a paper, and said that there was no actual 

 decrease at the higher level, but a diminished collection due to 

 eddy ; he added that he found a large gauge on the tower 

 caught much more than a small one. Mr. Rogers Field now 

 took the matter up, and setting dow n the va'ues so as to form 

 curves he showed :— I. That the ratio of the rainfall on the 

 tower to the rainfall on the ground depends on the force and 

 direction of the wind. 2. That when there is no wind the rain- 

 fall on the tower is about the same as the rainfall on the ground. 

 3. That when there is wind the amount of rain falling on the 

 tower will vary on different portions of the tower, the portion 

 nearest the point at whiclt the wind strikes the tower receiving 

 less rain than falls on the ground, and the portion farthest from 

 the point at which the w ind strikes the tower receiving the same 

 or more rain than falls on the ground. 4. That the excess of 

 rain falling on the portion of the tower farthest from where the 

 wind strikes will, to a large extent, compenate the deficiency of 

 rain on the portion nearest to where the wind strikes, but 

 whether to a sufficient extent to make the average amount of 

 rain falling on the tower equal to that fallmg on the ground 

 cannot be determined from these experiments. From tliese 

 conclusions it is clear that if the building be flat and large, the 

 fall in the middle of the roof ought to be nearly the same as on 

 the gr.iund, and in tw 1 instances this is so, first at Messrs. 

 Marshall's factory at Leeds, and secondly Mr. Dines on a roof 

 of 5000 sqnnre feet of area. Thus finally experimental evidence 

 has c rr iborated the views of Mr. Stanley Jevons, given above. 



Oil some of Bell and Painters Recent Researches and their 

 Conseipiciic s, by \Y. Lant Carpenter.— The author referred to 

 the researches of Messrs. Graham Bell and Tainter upon the 

 sonorcu ness of matter under the influence of a beam of inter- 

 mittent Ii_;ht, and de'crihed the receivers employed, in which 

 substances' are placed for examination. Porous substances gave 

 louder sounds than dense ones, and those of a dark colour 

 louder than light when a rapidly intermittent beam fell on 

 them. An apparatus had been contrived by Mr. Tainter for 

 measuring the relative sonorous powers of bodies, which was 

 descrihecf by the author. He also stated that it had occurred to 

 him that a modification of this apparatus might be employed for 

 audibly estimating the relative intensities of two lights when 

 intermittent beams fell from them upon tw i precisely similar 

 receivers. The author proposed to call this instrument an 

 audible photometer, and said that some rough experiments had 

 somewhat jnstified his expectations. 



