DercEMBER 17, 1896] 
IVA LORE 
163 
OUR ASTRONOMICAL COLUMN. 
“© BUREAU DES LONGITUDES.”’—The Annual for the year 1897 
is still as complete as ever, and is a necessary vade mecuni to 
the astronomer, physicist, and chemist. Our readers are so 
familiar with the usual contents of this compact littie volume, 
that we limit ourselves to summing up the chief alterations 
and additions. The table of minor planets has been completed 
up to September 7, 1896, the number of these bodies now 
amounting to 431. Cometary notices have been brought up to 
the year 1895, while several new values for double-star elements 
have been inserted. Among the articles, which are always of 
great interest, are three from the pen of M. F. Tisserand. The 
first is a masterly summary of our knowledge of the proper 
movement of the solar system; the second, on the fourth meet- 
ing of the International Committee for the completion of the 
photographic map of the heavens ; and the third, on the labours 
of the International Commission on fundamental stars. M. H. 
Poincaré writes on the kathode and Rontgen rays. M. J. 
Janssen discusses some epochs in the astronomical history of 
planets, and the work done at the Mont Blane Observatory 
during the present year. Several discourses are also included, 
namely, that delivered by M. A. Cornu at the funeral of’ M. 
Fizeau, and those delivered by M.M. Janssen, Loewy, and 
Poincaré at the funeral of the late Director of the Paris 
Observatory. 
**THE SYSTEM OF THE Wor LD.” —Inasmall pamphlet entitled 
**Unser Weltsystem” (Gustav Fock, Leipzig), Herrn A. F, 
Barth presents us with an essay on the movements of the 
bodies contained therein. Without going at all into mathe- 
matical reasonings, complicated by numbers, he limits himself 
to discuss in words the questions that arise. 
further movements due to perturbations, can be obtained. Not 
only are the earth’s motions discussed, but those of the moon are 
also taken in hand. 
what are the causes which give us different lengths of days, 
months and years, and how these may be converted into one 
another. These and several other points are touched upon, and 
the author concludes with a few general remarks on the extent 
of space. , 
Another pamphlet (Gauthier- Villars et Fils, Paris) contains an 
exposition of the mechanical formation of a ‘* Systeme du Monde,” 
after a new theory by Lieut.-Colonel du Ligondés. M. L’Abbé 
Th, Moreux is the writer of the essay, and he introduces this new 
idea to us after a short summary of previous hypotheses, such as 
those of Laplace and Faye. Assuming that motions in space 
can take place in all directions, then if there exist spots around 
which these movements are to a certain extent symmetrical, and 
if such a region be more or less homogeneous, then disturbances 
will be equally symmetrical in every direction, and a nearly 
round mass will be formed. The next stage in the development 
of this mass is its change of shape from circular to lenticular. 
This is brought about by the particles circulating towards the 
interior of the mass, and therefore coming into collision with 
one another. With condensation the mass becomes less homo- 
eneous, and the law of gravity becomes modified. A general 
deformation of all the orbits of the particles commences, and 
finally a lens-shaped mass is the result. A ring now begins to 
be formed, having its point of greatest density some distance 
from its centre. The values of gravity vary along a radius, being 
small at the centre, reaching a maximum some distance away, 
and finally vanishing. The point of maximum velocity coincides 
with the maximum value of gravity. The ring becomes now the 
centre of attraction of bodies lying near it. Stresses are set up 
and a rupture takes place, this ring being split into three parts. 
At a later epoch the conditions are such that another ring of small 
dimensions is formed; this forms a second maximum point 
of density on the flat disc, which eventually is ruptured. These 
rings finally condense and form the several planets. The theory 
accounts for the different densities, sizes, rotations, and velocities 
of the planets, and also for the cases of the satellites. Space 
forbids us, however, from going into this theory more in 
detail, but there are several good points about it which make it 
interesting. 
““COMPANION TO THE OBSERVATORY.” —This annual for the 
year 1897 contains the usual amount of useful information, and 
the arrangement remains as formerly. Mr. Denning gives the 
list of principal meteor showers for the year, but we are surprised 
to see that no additional information is given of those swarms 
NO. 1416, VOL. 55 | 
In this way a clear | 4,500,000 gallons per acre daily, and its bacterial efficiency 
idea of the movements of the earth round the sun, and also those | 
One may here, among other things, learn | 
| bacterial efficiency in proportion to their period of service. 
| the filters but from the delivery pipes. 
which will be of special interest during the next year or two. 
Data for the total solar eclipse which will occur on January 21, 
1898, in addition to the two annular eclipses in 1897, are given, 
An ephemeris for Jupiter’s fifth satellite up to the middle of 
May also receives a place, but its accuracy is doubted, for, as Mr. 
Marth says, no recent measures have been made, so that the 
adopted daily rate of motion is based on measures made in 1892 
and 1893. The variable star information is very full and 
complete ; but, if we may venture to make a suggestion, the table 
giving the mean places for the year 1897 would be made more 
useful if the approximate periods were to be placed against 
each star. 
BACTERIAL WATER PURIFICATION. 
“THE twenty-seventh annual report of the State Board of 
Health of Massachusetts for 1895 has just been issued. 
This is the eighth year that the valuable experimencal work. of 
the now famous Lawrence Experiment Station has been con- 
tinued, Although no very remarkable novel features have been 
recorded in the practice of bacterial water. purification, jit 4s 
highly satisfactory to find that the previous important work of 
the station is fully confirmed by the investigations conducted 
during the past year. An interesting point to which attention 
is called is the tendency exhibited by sand-filters to increase in 
In 
support of this the working of the oldest experimental ‘filter at 
the station, and one of those with the greatest effective size of 
sand grain, is cited. This filter in 1893, filtering at an average 
rate of 2,000,000 gallons per acre daily, had a bacterial efficiency 
equal to 96°75 percent. ; during 1894 its rate of filtration was 
reached 98°97 per cent., whilst in 1895, although working at 
approximately the same rate as in the previous year, its bac- 
terial efficiency rose to 99°57 per cent. This increased bacterial 
efficiency, caused by greater length of service period, was ton- 
siderably more marked in the case of filters constructed of 
medium coarse or coarse sands than with those in which 
medium fine sand was employed. It would be out of place in 
these columns to discuss the various technical questions dealt 
with in the report, but there is one point which is very clearly 
brought out, and which is of particular interest in connection 
with the controversy which has recently arisen over the bacterial 
examinations of the London water-supply. An attempt has been 
| made more than once to discount the value attaching to early bac- 
terial examinations of the London waters, which first exhibited 
the efficiency of the purification processes employed, on the ground 
that the samples for investigation were not cullected direct from 
It has been contended 
that the numerical results obtained from samples drawn from 
the mains do not represent the bacterial efficiency of the purifi- 
cation processes in operation at the works, and this contention 
is based upon the hypothesis that the bacteria present in the 
effluent multiply in the pipes before delivery. The examina: 
tions made at the Lawrence Experiment Station show that 
there is no foundation whatever for this supposition. Thus in 
the monthly averages of daily bacterial examinations made of the 
Lawrence water conducted over six months, we find the raw 
river water contained 7533 bacteria per cubic centimetre, the 
effluent taken direct from the filter 134, the reservoir outlet 119, 
and the samples taken from the City Hall tap 86 bacteria per 
cubic centimetre. These results are sufficiently striking and 
instructive, and require no further comment. Another point to 
which considerable interest attaches is the effect upon the total 
number of bacteria which appear upon a gelatine plate, pro- 
duced by the time during which the latter is kept and the 
colonies counted. Thus a water-plate poured from raw river- 
water exhibited 913 colonies per cubic centimetre on the first 
day, after two days the number rose to 8613, alter three days to 
12,317, whilst after four days they numbered 15,017 per cubic 
centimetre. Similarly in a sample of the same water filtered, 
whilst only three colonies could be counted on the first day, 48 
made their appearance after two days, 72 after three days, and 
87 per cubic centimetre after four days. The bacteriological 
examination of water, it cannot be too frequently insisted upon, 
is surrounded with subtle pitfalls into which the unwary may 
very easily be decoyed, and if the method is to take its position 
as a scientific process, too much attention to the details upon 
which its accuracy depends cannot be expended. In conclusion, 
in the section devoted to bacteriological technique, we note the 
