“Oct. ‘T, 1885] 
NATURE 
537 
Courteney Fox.—The laws enunciated in this paper are deduced 
empirically from observations extending over the last seventy 
years. Even as detached laws they are of great value; but 
their importance is more evident when we consider that, as the 
author remarks, it is from such material that the future science 
‘of meteorology must be built up by cautious induction. Given 
that a certain month of season is in certain condition as regards 
temperature or rainfall, Dr. Fox seeks to determine what may 
be predicted of the succeeding period as regards these qualities. 
He finds that, if a spring or a summer be very cold, the succeed- 
ing season will be cold; and warm autumns succeed very 
warm summers. The fact of a very dry August being followed 
by a wet September is unique. The following table shows 
other results obtained. 
Characteristics. | Month. Month following. 
Very cold | Jan, April, June, 7 
July, Aug., Sept., Dec. | so 
Very warm | Jan. Dry 
June, July, Aug., Warm 
Very dry June, July, Warm 
Very wet Jan., March. April, | Warm 
May, July Cold 
In addition the author records what follows when a given 
moath has marked temperature and moisture characteristics 
simultaneously. 
Characteristics Month Month following 
—————a 
| 
Warm and wet | Nov., Dec., Wet 
| Jan., Warm 
Warm and dry | June, July, | Warm 
| Aug., | Wet 
Cold and wet | July, Aug., | Cold 
Cold and dry Dec., Cold 
Nov. Dry 
| 
A very cold and very wet summer is succeeded usually by a 
cold autumn. 
Domestic Electric Lighting, by W. H. Preece, F.R.S. Elec- 
trician G. P.O.—After referring to the full details of the lighting 
installation of his house in Wimbledon, given to the section at 
the meeting at Montreal, Mr. Preece referred generally to the 
experiences he had gained during the past twelve months. The 
secondary batteries upon which he had mainly relied exceeded 
his expectations in the services they rendered. They returned 
70 per cent. of the energy put into them without any apparent 
diminution whatever in their E.M.F. They showed no signs of 
deterioration and gave no trouble whatever. He used his gas 
engine for charging only two days a week. He had experienced 
no fault with the wiring of his house. He had used only the 
very best materials, and had attended personally to the insulation 
of the system. It was periodically tested and found to be good. 
He referred in severe terms to the cheap and nasty wire which 
was so frequently and ignorantly used, and feared that the preju- 
dice against the electric light would increase when failures from 
this cause arose. None but the very best materials should be 
used, and the joints should be seen to by experts. He had de- 
voted considerable attention to the problem of distributing light, 
and had succeeded so far that while his rooms were beautifully 
illuminated the eye was not irritated by regarding a bright source 
of light. ‘lhe lamp he used was a 50 volt 10 candle power glow 
lamp, and it was, as a rule, so fixed that the eye never saw it. 
He had arrived at the use of these lamps after careful considera- 
tion and many trials of other lamps. ‘They secured greater 
safety in the leads, and involved less capital in batteries through 
the use of low E.M.F. He ran his lamp at an E.M.F. about 
2 per cent. less than the normal E.M.F. He did this to secure 
long life to his lamps. The breakage had been very small. The 
E.M.F. and current which will give a lamp a normal life of 
1,000 hours and a certain candle power should be determined by 
every maker. The sixth power of the current will give the 
candle power and the twenty-fifth power the life with any other 
current. The great advantage of batteries is that the proper cur- 
is ensured. If lamps are ran too low there is a waste of power, if 
too high there is a waste of lamps. We are now gradually ac- 
quiring a thorough knowledge of the number of Watts which 
should be expended in each lamp to secure the maximum economic 
efficiency. He had introduced into the charging lead and into the 
discharging lead a Ferranti meter, so that he was able to record 
exactly the quantity of electricity passed through the batteries 
and that passed through the lamps. This beautiful meter is 
based on Ampere’s laws which determine the attraction and re- 
pulsion of currents. A small phosphor-bronze vane is immersed 
in a bath of mercury, through which the current flows radially, 
fixed in a magnetic field. The mercury rotates and carries with 
it the vane. The rate of rotation varies directly with the 
strength of current and the number of rotations are recorded by 
a counter, which can be read off directly. So far he was per- 
fectly satisfied with its performance. As regards expense, ex- 
cepting the first cost, he did not find much addition to his ex- 
penditure for illumination. His electric light was costing him 
about 50/. a year for gas, wages, oil, and lamps. It was the 
cheapest luxury he indulged in. The great advantages were the 
comfort and cheerfulness it engendered, and as cheerfulness was 
the main element of health he thought that the electric light 
would prove a serious rival to the doctor. There was no one 
who valued health and comfort who should neglect to apply the 
electric light to his home, when it was brought, as it has been by 
the success of the secondary batteries, within his means. It was 
said that he, as an expert, could make things go which would 
fail in ordinary hands; but he mentioned several cases where 
coachmen, butlers, gardeners, and grooms had been found 
Eecetly competent and intelligent enough to attend to every- 
thing. 
Discussion on Standards of White Light.—This discussion 
was not so well sustained as the discussion on the kinetic theory. 
All the speakers agreed with the adoption of the pentane standard 
for commercial purposes. For scientific purposes a definition in 
terms of energy was deemed necessary. The eye cannot be used 
as an accurate instrument. On this point Prof. Stokes referred 
to the fact that if two equal areas differently coloured seem to 
have equally intense illumination, we have only to alter the size 
of the common area to destroy the apparent equality of intensity. 
On Photometry with the Pentane Standard, by Mr. A. Vernon 
Harcourt.—Mr. Harcourt described the construction of the 
pentane standard light, and the method of using it for photo- 
metric purposes. In the course of his remarks he referred to 
the meaning of the expression ‘‘ white light.” Any so-called 
standard of white light is more nearly a standard of yellow light. 
He had never got a satisfactory definition of the expression, but 
supposed it to be such light as we have in ordinary daylight. 
The Constitution of the Luminiferous Ether on the Vortex 
Atom Theory, by Prof. W. M. Hicks.—The simple incompress- 
ible fluid necessary on the vortex atom theory is quite incapable 
of transmitting vibrations similar to those of light. The author 
has therefore considered the possibility of transmitting waves 
through a medium which consists of this fluid modified so as to 
contain small vortex rings closely packed together. The rings 
are supposed to be composed of the same material as the rest of 
the fluid, to be very small compared with the wave-length, and 
to be at distances from one another also small compared with 
the wave-length. Their motion of translation is als» taken to 
be so comparatively slow, that very many waves can pass over 
any one before it has much changed its position. Such a medium 
would probably act as a fluid for large motions. The vibration 
in the wave front may be (1) swinging, such as a ring oscillating 
on a diameter ; (2) transversal vibration of the ring ; (3) vibra- 
tions perpendicular to the plane of the rings; (4) apertural 
vibrations. Of these (3) seems to be impossible. If 7 be the 
radius of the rings, / the distances of their planes, w their cyclic 
constant, and v the velocity of translation, the author found 
w 7) 
- MCS —i(— 5 
TONG? 
wir? 
Ses SVE 
7(5) 
whilst for (4) in case of rings arranged parallel to a wave-front— 
For (1) . 
Hor(2)ce 475 
wrt? 
(22 + 47°)! 
On a Photometer made with Translucent Prisms, by Mr. J. 
uc 
rent once determined can never be exceeded, and thus efficiency | Joly.—In this photometer each side of the prism is illuminated 
