May 2, 1912] 
the afternoon amounts in December to 65 per cent. 
of the possible. From twenty-five years’ observations 
in Pavlovsk, it appears that in winter the maximum 
occurred later, and the afternoon sunshine was 
greater, in the clear months, that is, those in which 
the sunshine was above the average during the 
was the case. 
Tue Journal of the Washington Academy of 
Sciences for April 4 contains a summary of the results 
NATURE 
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227 
is much simplified by this process, which has the 
further advantage that solid or continuous lines in 
the original are not broken up as they are when 
reproduced by means of a lined screen. The author 
calls this process “ stagmatypie,” and gives two illus- 
” 
| trations of it which certainly show that the process 
period; whereas in the summer months the reverse | 
obtained by Messrs. Day and Sosman, of the Geo- | 
physical Laboratory of the Carnegie Institution, in 
their recent determination of standard melting and 
boiling points on the constant volume nitrogen 
thermometer and in terms of the thermodynamic 
scale. In some cases the determination was made 
directly, in others by the intervention of platinum- 
platinum-rhodium or copper-constantan thermo- 
couples. The following melting points were found :— 
cadmium 320:8°, zinc 419:3°, antimony 629:8°; and 
the following boiling points at normal pressure :— 
benzophenone 305-85°, sulphur 444-4°, on the constant 
volume nitrogen thermometer. These become on the 
thermodynamic scale 320:9°, 419:4°, 630:0°, 305-9°, and 
444°55° respectively. 
Two sets of measurements of the electric charge on 
rain made during last year are already available. 
The first, covering the short period March to June, 
were made in Dublin by Prof. McClelland and Mr. 
Nolan, and are published in the February Proceedings 
of the Royal Irish Academy; the second, from May 
to December, made at Puy-en-Velay, central France, 
by M. Baldit, appear in the March number of Le 
Radium. 
positive over negative electricity brought down by 
rain, and the Dublin observations show that large 
drops are nearly always positively charged. At Puy- | 
en-Velay the charge per cubic centimetre of rain is 
greater for negatively charged than for positively 
charged, while the reverse is true for Dublin. The 
mean electric current to earth per square centimetre 
of surface during rain, according to the Puy-en-Velay 
observations, is between 3 and 5 x 10-'* ampere. 
Dr. Hans Srrecker finds that if strong aqueous 
solutions of gelatine and gum arabic are shaken 
together they do not mix, but form an emulsion. On 
standing there is much agitation of the droplets of 
the one that is in the smaller proportion, they coalesce 
to a certain extent, and there results an even dis- 
tribution of spherical globules of an approximately 
equal size, the size depending upon various condi- 
tions. He describes in the last number (April 15) 
of the Revue générale des Sciences the use of such 
an emulsion in various photomechanical processes. 
It will take the place of the asphalt grain in photo- 
gravure, and it will serve instead of the lined screen 
in the making of half-tone blocks. For these pur- 
poses the gelatine is in excess, and the particles of 
gum in the dried film are less easily penetrated by 
the etching liquid than the gelatine in which they 
have been formed. The making of half-tone blocks 
NO. 2218, VOL. 89] 
Both sets agree in giving an excess of | 
| 
has the advantages claimed for it. 
In vol. iv., part i., of the Transactions and Notes 
of the Concrete Institute is contained an interesting 
photograph of a rag bolt found last summer 
embedded in a slab of concrete composed of Portland 
cement, ballast, and broken bricks. The concrete 
formed part of the foundations of the 1862 exhibition 
buildings at South Kensington, and had not been 
disturbed up to the time of its removal. The bolt was 
found when cutting through the concrete slab for 
some alteration in connection with the Imperial 
Institute, and was at ground-level. Both concrete 
and bolt were under cover. Only the top end of the 
bolt where exposed to the atmosphere, and the 
bottom end where embedded in the soil, were 
corroded; the remainder was quite clean, with the 
original blue scale thereon. This may be regarded 
as another proof that the reinforcement bars in ferro- 
concrete work will be preserved for an indefinite time 
| provided that the concrete is maintained free from 
cracks. 
OUR ASTRONOMICAL COLUMN. 
ASTRONOMICAL OCCURRENCES FOR May: 
May 3. 14h. 9m. Jupiter in conjunction with the 
Moon (Jupiter 5° 2’ N.). 
4. 2h.om. Mars at greatest heliocentric latitude 
N. 
7. 13h. 36m. Uranus in conjunction with the 
Moon (Uranus 4° 41' N.). 
5 23h.om. Uranus stationary. 
12. 15h. rom. Mars in conjunction with Neptune 
(Mars 2° 9’ N.). 
»  2th.om. Mercury at greatest elongation W. 
14. 6h.om. Saturn in conjunction with the Sun. 
I5. toh 45m. Venus in conjunction with the 
Moon (Venus 3° 11’ S.). 
16. oh. 11m. Saturn in conjunction with the 
Moon (Saturn 4° 58’ S.). 
20. sh. 1m. Neptune in conjunction with the 
Moon. (Neptune 5° 46’ S.). 
5, 12h. 4m. Mars in conjunction with the Moon 
(Mars 3° 42’ S.). 
27. 8h. 47m. Venus in conjunction with Saturn 
(Venus 1° 7’ N.). 
30. 5h. 49m. Jupiter in conjunction with the 
Moon (Jupiter 4° 48’ N.). 
31. 22h.om. Jupiter at opposition to the Sun. 
CometTarY SpeEctrA.—In an article recently noted 
in these columns, MM. Pluvinel and Baldet, while 
agreeing as to the identity of certain doublets in the 
spectra of Morehouse’s comet with similar doublets 
in Prof. Fowler’s spectrum of carbon monoxide at 
very low pressure, pointed out that only twelve of 
their twenty-one cometary bands were represented in 
the published laboratory spectrum, and of these 
twelve there were serious discrepancies of wave- 
length in two cases. 
Prof. Fowler now points out (Astrophysical 
Journai, vol. xxxv., No. 2) that there are probably 
