156 
NATURE 
[ApriL 8, 1915 

microscopic work. In his experiments the author has 
used the soft rays from a tube provided with a lithium 
glass window. The rays can only pass out of the lead 
chamber in which the tube is enclosed through a series 
of fine holes in lead screens in line with each other, 
and in consequence they strike the photographic plate 
as a parallel beam. The object to be photographed is 
placed in contact with the plate, which is enclosed 
in a light tight box. Plates with thin gelatine films 
and very fine grain must be used. The time of expo- 
sure depends on the thickness and opacity of the object, 
and the author prefers to use the harder rays from 
the tube as the opacity increases. The resulting 
photographs are the same size as the object, and must 
be enlarged by the usual photographic method. Six 
reproductions of photographs showing the internal 
structure of microscopic objects are given in the paper. 
Tue Rendiconti of the Italian Chemical Society 
(vol. vii., pp. 173-222) has an interesting discussion 
of the relationship existing between Mendel’s principles 
of heredity and the atomic theory by Prof. C. Vulpiani. 
A brief survey is given of the recent developments of 
our views as to the atomic and molecular state, and 
an attempt is made to show that the natural basis of 
the hereditary elements which are transmitted accord- 
ing to Mendelian laws is to be found in the molecular 
or atomic groupings present within the cells, and of 
which the chromosomes are only the outward visible 
manifestation. The author very justly emphasises 
how the Mendelian laws of heredity have led to a 
more general recognition of the complexity of cell 
protoplasm. The view that each hereditary element 
corresponds with some material factor in the ultra- 
microscopic or molecular structure of the contents of 
the reproductive cells will undoubtedly lead to more 
correct conceptions being formed as to the nature of 
cell protoplasm than those which have in the past been 
current among biologists. 
A papER on the processes of manufacture of wrought 
iron and steel tubes was read by Mr. J. G. Stewart 
at the Institution of Engineers and Shipbuilders in 
Scotland on February 16. The author states that it 
is very rarely that potable waters are found to have 
any appreciable corrosive effect on steel pipes, and 
quotes several instances of pipes which have been in 
service many years with very little deterioration. The 
principal fear is for the outside of the pipes. Most 
natural ground, especially clay, is not only innocuous, 
but is actually a permanent protection to steel pipes 
from corrosion. In some cases where the pipes are 
laid through artificially made, or alluvial ground, 
external protection is desirable. The want has been 
met by dipping the pipes in a hot bath of Dr. Angus 
Smith’s or other bituminous solution, and in cases 
where the ground contains an excessive amount of 
salts and acids which cause corrosion, the additional 
precaution is taken of wrapping the pipes in coarse 
jute Hessian cloth saturated with the hot solution, 
winding it spirally on the already coated pipe. 
Tue March number of the Journal of the Franklin 
Institute contains a paper on paints to prevent elec- 
trolysis in concrete structures, by Mr. H. A. 
NO. 2371, VOL. 95| 



Gardner, assistant director of the Washington In- 
stitute of Industrial Research. An extensive series 
of experiments on iron rods of 1/2 or 3/4 in. diameter 
embedded in concrete cylinders 1 ft. long has been 
carried out by the author to determine what type of 
paint was most effective. The rods were thoroughly 
cleaned, and two coats of the paint applied, each 
being allowed a week to dry. They were then em- 
bedded in the concrete, which was aged for a month 
before the test was commenced. Each cylinder was 
then immersed in water, and a potential difference 
of 30 to 100 volts applied for 10 days between two 
rods in each cylinder, or between one rod and an 
outside electrode, the current transmitted being 
observed. In all cases in which an appreciable current 
passed, the concrete cracked round the anode. The 
uncracked cylinders were tested for the strength of 
the bonding between the iron and the concrete. The 
author concludes that the paint should be prepared 
from boiled or bodied oils which dry by polymerisation 
rather than oxidation, that the pigments should be 
insulators and should give a rough surface, and that 
the paint should have fine sand scattered over it before 
it is quite dry. 
WE are asked by the proprietors of the Mallock- 
Armstrong ear defender described in last week’s 
Natur (p. 131) to say that since January 1 of this year 
all the defenders sold have been of an improved pat- 
tern, furnished with gold-plated gauze wire to resist 
corrosive effects—such as those of sea air—and gener- 
ally are more expensive to make than those first put 
on the market. Accordingly the price is now 4s. the 
pair, instead of 3s., as stated in our notice. 

OUR ASTRONOMICAL COLUMN. 
Comer 1915a (MELLISH).—The following is a con- 
tinuation of the ephemeris given last week :— 
ee (true) Dec, (true) Mag. 
-_m Ss & F 
April 10 18 14 8 --3 68 ... 841 
Tana 16 21 3 32:3 
ia Soe 18 32 35077 aS. 
1) ae 20 42 - 4 293 
TS: Gg... 1S 22) /5(0eeee wes nl eZ 
The comet is situated a little to the east of 9 Ser- 
pentis. 
MEASURES OF SATURN.—From December, 1913, to 
March, 1914, Prof. Percival Lowell made a series of 
measures of the ball, rings, and satellites of Saturn 
with the 24-in. of the Lowell Observatory. They were 
taken, as he states, ‘‘ with an eye to the irradiation,” 
and the measures have been deduced to what is com- 
monly taken as the mean distance. These are now 
presented by the author in a communication to the 
Lowell Observatory Bulletin No. 66 (vol. ii., No. 16). 
The diameter of the ball as determined from direct 
measures, measures of satellites, and measures of 
B ring is first given, followed by measures of the 
radius of the ball, breadths of B and A rings, and 
width of Cassini’s division. All these are summed 
up in a table giving the means of the measures for 
mean distance, followed by a table of the direct 
measures of the diameter of Titan. - 
STARS WITH VARIABLE RapiAL VELOcITIES.—Several 
communications are contained in No. 267 of the Lick 
Observatory Bulletin. The first, by Mr. R. E. Wilson, 
