272 
NATURE 
[Fucy 23, 1885. 
1/1toth of an inch in diameter, and are spherical or oblong 
in form, the translucent membrane appearing under the micro- 
scope to be composed of minute particles and spicules imbedded 
therein. 
As my observations included the examination of surface-life, 
the tow-net was continuously employed, and was always rapidly 
filled with so much gelatinous substance that it was difficult to 
pick out the Copepoda or other pelagic life. But although all of 
the bodies were perfect in form when taken in a bottle, the rush 
of water into the tow-net was sufficient to fracture them, the 
result being a mass of broken gelatinous déby7s (apparently 
vegetable) which clung tenaciously to the muslin of the net. 
They appeared to be most numerous a few feet below the 
surface, and are distinctly visible on looking down into the water 
from the boat-side. Weather does not seem to affect them, 
being apparently equally prevalent on a calm ora rough day ; 
but I noticed while rowing across from Penmaenmaur to Puffin 
Island, a distance of seven miles, that they were less plentiful 
about the middle of the entrance to the Menai Straits than 
nearer each side. 
Early in June they were in profusion about the mouth of the 
Dee. Associated with them I have invariably found quantities 
of octiluca, which soon congregated about the surface of the 
collecting-jar, while the gelatinous spheres remained suspended 
in the water, and the dés77s from the tow-net fell to the bottom. 
Any light that can be thrown upon the nature and appearance 
of these curious bodies will be much esteemed. 
Liverpool, July 16 Isaac C. THOMPSON 
The Banner System of Drainage 
Our attention has been called to a paragraph in NATURE 
(p. 221) in which you review, ‘‘ Hygiene, a Manual of Personal 
and Public Health,” by A. Newsholme, M.D., Lond. In your 
review or criticism you state that you ‘‘do not agree with Dr. 
Newsholme in thinking the ‘ Banner system of drainage one to 
be recommended,’” and you say your system coincides with 
that of several practical sanitarians. Now, as this is calculated 
to do harm, and as our system Aas been approved of by the most 
eminent sanitarians, and has also obtained the highest awards 
at all the most important exhibitions, including a Gold Medal at 
the Health Exhibition, 1884, and has been successfully applied 
to many noblemen’s mansions, hospitals, and other important 
public buildings, as well as to thousands of houses, we hope you 
will think we are justified in asking you to tell us your reasons 
for expressing the unfavourable opinion you have, and that you 
will oblige us with the names of the ‘‘ practical sanitarians”’ you 
refer to. 
We are unacquainted with Dr. Newsholme, and until the 
paragraph in NATURE was pointed out to us we were not aware 
of the existence of such a gentleman. Nevertheless, in fairness 
to him as well as to the public, we will thank you to insert this 
in your next issue. 
BANNER BROTHERS AND Co., 
per MANAGER 
11, Billiter Square, E.C., July 14 
[Exception having been taken by Messrs. Banner & Co. to a 
statement which appeared in our last issue in the review of the 
Elementary Text-books of hygiene, having reference to this 
system, we have no objection to state that (in the opinion of our 
reviewer) the Banner system, although correct in principle, is 
unnecessarily complicated in the details of its working. The 
“Banner Patent Closet” shown in diagram in the book referred 
to is a modification of the pan-closet, a closet which has been 
universally condemned and as almost universally acknowledged 
to be incapable of improyement.—ED. ] 
ON THE USE OF CARBON BISULPHIDE IN 
PRISMS 
ie the American Journal of Science for April, 1885, 
there is an account of some experiments of Dr. 
Draper’s which will be read with great interest by all who 
have used liquid prisms in a spectroscope. The following 
is an abstract of the article :— 
The photographs which were taken in the research on 
the presence of oxygen in the sun were obtained by the 
1 Being an account of experiments made by the late Dr. Henry Draper, 
of New York. 
use of two hollow prisms filled with carbon bisulphide. 
The same prisms had been used by Mr. Rutherford to 
produce his celebrated solar prismatic spectrum. The 
photographic work for the oxygen research was done in 
New York in a back room of the third storey of Dr. 
Draper’s residence. The temperature of the room was 
remarkably uniform and the definition was all that could 
be desired. When, however, the research was continued 
in the new physical laboratory which Dr. Draper com- 
pleted in 1880, it was found practically impossible to 
use carbon bisulphide prisms in the room owing to the 
rapid variations of temperature. No definition whatever 
could be obtained with the same prisms which had per- 
formed so well previously. In consequence the use of 
these prisms had to be abandoned and a series of experi- 
ments made to obtain the spectrum by other means. A 
Rutherford silvered glass grating of 8640 lines to the inch 
and a train of six flint glass prisms made by Steinheil 
were each tried. The grating was not found satisfactory, 
partly because want of light rendered long exposure 
necessary, partly because the definition was not so good 
as had been originally obtained from the bisulphide 
prisms. The flint prisms gave excellent definition, quite 
as good as had been obtained with the bisulphide prisms, 
but there was less light, and it was found impossible to 
get the line H on the photographic plate, through the 
train. The dispersion between G and H with the six 
flint prisms was not quite so great as with the two bisul- 
phide of carbon prisms. 
Among the earliest experiments which were undertaken 
in the new laboratory was a series made to test the per- 
formance of a bisulphide prism of Thollon’s construction, 
made by Hilger, of London. This prisms consists of a 
glass bottle having two plane sides, making an angle of 
go° with one another, upon which are cemented two 
prisms of flint glass 4 by 2 inches on the face, having 
each a refracting angle of 18°. The refracting edges of 
these glass prisms are opposed to that of the bisulphide 
prism. Hence the refracting angle of the compound 
prism is 54°. The same difficulties were experienced with 
this prism as with the Rutherford bisulphide prism. 
Owing to the temperature variations the lines were 
“woolly” and no definition was possible. It was found 
that the dispersion power of the Thollon prism was equal 
to that of about four of the Steinheil flint prisms ; and this 
fact, together with the unsatisfactory character of the 
results obtained with the train of prisms as well as with 
the grating, led Dr. Draper to undertake an investigation 
into the cause of this unsteadiness of the bisulphide with 
a view to remedying it if practicable. 
While using these prisms Mr. Rutherford made an im- 
portant observation. He noticed that if a good prism 
which, with a high power, refuses to define the soda line 
(a more stringent test than soda lines), is violently shaken 
and then placed in position, it will fora few minutes define 
beautifully, but gradually settle to its former condition. 
It occurred to Dr. Draper, therefore, that possibly the 
striz caused by convection-currents produced by in- 
equalities of temperature, and which caused the bad 
definition, might be destroyed by an active agitation of 
the liquid. He therefore placed a small propeller wheel 
in the bisulphide contained in the Thollon prism, passing 
its shaft through the stopper so that he could drive it at 
any desired speed by an electro-motor. The result was 
marvellous: by thus keeping the liquid in agitation all 
inequalities in its density were prevented, and the defini- 
tion became excellent. Thus arranged, the Thollon prism 
was found to be superior, especially in quantity of light, to 
the Steinheil train of prisms. 
Now another source of error was developed. Although 
when the propeller was running the definition of the bi- 
sulphide was not affected by changes of temperature, yet 
now these changes of temperature, by changing the re- 
fractive index of the liquid, caused a continual shifting of 
