Oscar Grim describes Bacteria and Vibriones from his own 
investigations in the Archiv fur Mikrosc. Anatomie. He has 
observed their conjugation and fissiparous multiplication, and 
also has seen leucocyles breaking up into granular matter which 
ultimately assumed the form of Bacteria. ’ 
Pror. MOLteER, of Lund, Sweden, has published the Ephe- 
_ merides of Faye’s comet for its next return to the neighbourhood 
of the sun. It will be in perihelion about July 18, and will 
continue to approach nearer and nearer to the earth till Jan. 10, 
1874. It will not, however, be in a position favourable for ob- 
servation, and it is very probable that not even the most powerful 
telescope will be able to catch it. 
M. Caras in Zes Mondes endeavours to account for a dry 
haze (4rouillard sec) which is seen in the atmosphere at certain 
seasons in particular countries. At Paris he says it is clearly 
visible on the horizon on the morning of lovely summer days, 
and is regarded as the presage of fine warm weather. It is of a 
light roseate hue. In proportion as the day is dry and warm, 
- the denser and higher above the horizon is the haze. This haze 
is seen at all heights, having been observed by Saussure in 
Switzerland, by Lecay and Charles Martin in Auvergne, and by 
~ Wilkomer in Spain; in all cases, the phenomenon is seen at its 
best when the day is dry and warm. M. Callas attributes it to 
the combustion of aerolites and shooting stars. The attraction 
of the earth, he says, causes these bodies to deviate from their 
regular course and to be precipitated to the earth’s surface with 
a rapidity which certainly exceeds 20 kilometres per second, and 
which is sufficient to set them on fire and render them vola- 
tile. The vapours thus produced rapidly become so rarified 
that they may be looked upon as the ultimate limit of 
divisibility of insoluble bodies and form the dry mists alluded to, 
Obeying the law of gravity these descend to the earth from the 
heights where they are formed, slowly however, on account of 
their extreme tenuity. As they approach the earth they come 
under the influence of winds which dissipate them, and of cold 
moisture, which absorbs them. Hence it is that they are per- 
ceived only in certain countries and in warm seasons ; especially 
in Spain, and on the table-lands of Abyssinia and Mexico. 
M. Callas thinks that the haze may be regarded as a sort 
of cosmical matter akin to that which composes the tails of 
comets. The hypothesis has the merit of being at least curious, 
and so far as we know, original. 
THE first paper in the last number of the Bulletin of the 
French Geographical Society is in connection with a well-exe- 
cuted map of the chief physical features of Eastern Brazil, 
appended to the number. M. Charles Grad contributes a long 
article on the geology of the Algerian Sahara and its system of 
waters. Perhaps the most interesting article is by M. Paul 
Gaffanel on the Great Sargasso Sea in the middle of the Atlantic, 
the history of which he traces from the Phcenicians downwards, 
describes its geography historically and with reference to what is 
known of it at present, which seems to be comparatively little, 
and concludes by pointing out that the wrack or algse of which it 
is composed might be put to immensely profitable industrial 
uses. 
WE have received the prospectus of the new Italian Geo- 
graphical Magazine, whose first appearance we announced last 
week. Dr, Petermann has written a very hearty preface for his 
young friend, the editor, Guido Cora, whose plan is very compre- 
hensive, embracing not only geography proper, but also geo- 
gnosy, botany, zoology, anthropology, ethnography : hence the 
name of the magazine,—Cosmos, We wish it ample success. 
THE Revue Scientifigue for Feb. 8 contains Dr. Liebreich’s 
Royal Institution lecture on the effect of School Life on Vision 
in the Young, 
SIR W. ARMSTRONG ON 1HE COAL 
QUES TION * 
VM 
A? the present moment attention is being drawn to a new 
method of increas ng the efficiency of the steam engine by 
pumping heated air into the boiler. It is impossible to conjecture 
what theoretical considerations could have led Mr. Warsop, 
the discoverer of the system, to anticipate beneficial results 
from the adoption of such an expedient, and yet the experiments 
that have been made in proof of its efficacy are so authoritative 
that they cannot be repudiated on the ground of their being un- 
supported by theory. This subject, alihough much debated of 
late, is still so ambiguous and obscure that I shall take the pre- 
sent opportunity of stating the difficulties of the case in the hope 
of eliciting satisfactory explanation. Mr. Warsop’s method con- 
sists in attaching to a steam engine a forcing pump for the 
purpose of injecting air into the boiler. The pipe from this 
forcing pump is formed into a coil in the flue so that the air may 
absorb a portion of the waste heat. Aft r entering the boiler 
the pipe is laid along the bottom, and being perforated with holes 
allows the air to bubble up through the water at many different 
points. The result appears to be that, with a given expenditure 
of fuel, the available power of the engine is considerably in- 
creased by the action of the air-pump, notwithstanding that the 
power for working it is derived from the engine itself. How, 
then, is this to be explained? It is clear that air forced into a 
receiver cannot without the aid of extraneous heat give back all 
the power expended upon the forcing pump. There must of 
necessity be loss of power by friction, and also from the im- 
possibilijy in practice of realising all the expansive action of the 
condensed air corresponding to the compressive action of the 
pump prior to actual injection taking place. It would be a liberal 
estimate to assume that one-half of the power expended on the 
pump is recoverable from the air. Hence, to make up the defi- 
ciency by the application of heat, we should have to double the 
volume of the air, which would require it to be heated to up- 
wards of 500° F, above its initial temperature. Now, in the case 
of the Warsop arrangement, considering the inconsiderable heat- 
ing power of the escaping gases to which the air-pipe is exposed ; 
considering also the slow absorbing power of air, and the small- 
ness of the surface presented by the coiled pipe, it is hard to 
believe that the air could enter the boiler at such a temperature 
as I have named ; but even if it did, where is the surplus power 
to be found that gives the engine a palpable increase of efficiency? 
The mere reaction of the compressed air, with all the aid it can 
possibly derive from the absorption of waste heat, would barely 
save a loss, and certainly could never account for an important 
gain. It seems obvious, therefore, that whatever beneficial action 
is exercised by the air must be of an indirect nature, and not the 
immediate effect of its mechanical energy. A 
Four modes of action have been put forward to account 
for the effects obtained. Firstly, it is said that the air, in bub- 
bling through the water, facilitates the disengagement of the 
steam. This may very possibly be the case, for we know that 
water, entirely deprived of air, may be heated in an open vessel 
to a temperature greatly exceeding the usual boiling point, before 
ebullition commences. The reason of this is, that the adhesion 
between the water and the containing vessel, and also between 
the particles of water themselves, is sufficient to restrain the 
formation of steam at the usual boiling heat, unless air be pre- 
sent to afford points of separation. So far the explanation is 
plausible; for if the abstraction of air from water rai-es the 
boiling point, we may infer that the addition of air will 
lower it. But the reduction of the boiling-point within 
any supposable limits, would not lessen the quantity of heat 
required for the production of the steam sufficiently to 
afford a solution; because the sum of the latent and sensible 
heat, though not constant, as was formerly supposed, does not 
vary in relation to the boiling point to such an extent as would 
account for any important saving in that direction, A tangible 
advantage might, however, accrue from the accelerated trans- 
mission of heat from the fire to the w:ter, caused by the increase 
of difference which a lowered boiling pvint would occasion between 
the temperature of the water and that of the fire and gaszs acting 
onthe boiler ; but in the absence of thermometric experiments to 
show how much the boiling point is actually reduced, and how 
much the escaping gases are cooled, it is impossible to form any 
definite opinion as to the amount of this saving. It is certain, 
however, that unless the reductions of temperature be greater 
* Continued from p, 272, 
