May 4, 1899] 
cubic. Capelli has continued his researches on the re- 
ducibility of algebraic equations. Papers dealing with 
kinematical considerations have been published by 
E. Cavalli and C. Pietracola. The theory of groups 
forms the subject of papers by G. Bagnera and G. Fano ; 
while the geometry of hyper-space and non-Euclidian 
geometry have received contributions from R. Banal, E. 
Bertini, L. Berzolari, L. Bianchi—-Berzolari’s paper being 
on an extension of Meunier’s and Euler’s theorems to 
hyper-spaces. 
Of papers on higher geometry, we may note those of 
F. Enriques on the double planes of linear order f'’) = 1, 
and on surfaces which possess a sheaf of rational curves : 
besides other papers by F. Amodeo, E. Ciani, B. 
Levi, M. Pieri, P. Pizzettii and E. Veneroni. The 
Wronskian determinant has been treated by E. Borto- 
lotti and P. Vivanti. A number of papers dealing 
with questions chiefly of analysis have appeared by 
U. Amaldi, P. Burgatti, E. Bortolotti, T. Cazzaniga, S. 
Pincherle, U. Scarpis, C. Severini, and others. A review 
‘of Italian mathematical work would not be complete 
without some reference to G. Vailati’s historical papers, 
dealing chiefly with the early theories of mechanics. 
Passing to astronomy, we find that P. Tacchini has 
continued his observations on the sunspots, protuberances 
and faculze at the Roman College during the year. 
Observations have been contributed by E. Millosevich on 
the comet Perrine, on the planet DQ, 1898 (433), and on 
the last intrajovial planets. Contrary to the common 
opinion that the astronomy of the ancients was based 
exclusively on the geocentric hypothesis, Schiaparelli has 
shown that Heraclitus Ponticus, a disciple of Plato, had 
already adopted the theory that the sun was the centre of 
the orbits of the planets, while the earth remained the 
centre of the universe, and of the lunar and solar rota- 
tions—a system substantially that of Tycho. 
A considerable number of additions to our knowledge 
of terrestrial physics have appeared during the year. 
Seismology has been well represented by G. Aga- 
mennone, who has occupied himself with determining 
the velocities of propagation of the earthquakes of Aidin 
and of Pergamos (Asia Minor) of 185, and the 
earthquakes of India, of Labuan, and of Hayti of 1897 ; 
while P. Tacchini has considered the Emilia earth- 
quake of 1898. Volcanic phenomena have been closely 
observed on Vesuvius by R. V. Matteucci. The year 
1898 witnessed the rare appearance of flames on the 
volcano, which have been attributed by Semmola to jets of 
incandescent gas at a high temperature, unaccompanied 
by combustion ; while Matteucci differs in thinking that 
these flames are due to the imprisonment of inflammable 
substances. The formation of a cupola of lava on 
Vesuvius forms the subject of another note by Matteucci. 
A highly promising field of research has been opened up 
in a paper, by the same writer, on the physics of flowing 
lava, dealing with the effect of artificial refrigeration on 
the crystallisation of the magma. The probable presence 
of coronium in the gases of the Solfatara and of Vesuvius 
is dealt with by F. Anderlini, R. Nasiniand R. Salvadori. 
Bassani describes the formation of a small vent in the 
Solfatara. 
F. Morano, in his experiments on the thermal conduct- 
ivity of the rocks of the Campagna, has added fresh links 
of evidence on that debatable point, the age of the earth; 
while the second bone of contention betwixt mathe- 
maticians and geologists—the glacial period—forms the 
subject of a note by L. De Marchi, in reply to objections 
of Arrhenius. 
G. Folgheraiter has recently continued his investigations 
on the secular variations of magnetic dip as revealed by 
the magnetisation of ancient vases. At the observatory 
of Capodimonte, the variations of the magnetic elements 
have been closely studied by F. Contarino and V. 
Tedeschi, the latter concluding that at the present rate 
NO. 1540, VOL. 60] 
NATURE 9 
of decrease, the magnetic declination would vanish in 
113 years. 
F. Angeletti has devoted his attention to the rectifica- 
tion of the terrestrial meridian, and has found for the 
earth’s quadrant’ the value 10,000,855°76477 metres. 
On Mount Etna and its neighbourhood an important 
series of meteorological and gravitational observations 
have been carried out by A. Riccd. E. Oddone, working 
in the neighbourhood of Pavia, has investigated local 
variations of gravity, and the distribution and circulation 
of underground waters. Finally, a series of observations 
has been carried out on the steamer Asfromonte on the 
temperature and colour of the waters of the Adriatic and 
Ionian seas, of which A. Ricco and G. Saija have pub- 
lished a general vésumeé. 
Passing from the physics of the earth to physics proper, 
a prominent place must be given to E. Villari’s 
investigations on the Réntgen rays, referring more 
especially to their action in promoting the discharge of 
electrified bodies. Various experiments made by screen- 
ing these rays off partially by the aid of tubes, all tend to. 
the conclusion that the rays do not themselves promote 
the discharge, but cause it by means of the air on 
which they act. The diffusion of Réntgen rays and the 
influence of secondary rays emitted by bodies on which 
they fall have been considered at some length by R- 
Malagoli and C. Bonacini, whose views have been 
criticised by Murani. A. Battelli has continued his 
investigations on the nature of Réntgen rays by exam- 
ining the analogy between these and kathodic rays. 
Other properties of R6ntgen rays are dealt with by 
G. Guglielmo, A. Roiti, A. Sandrucci and others. 
Several papers have appeared from the pen of that fertile 
physicist A. Righi, dealing, among other points, with the 
kinematic interpretation of Zeeman’s phenomenon, and 
with the absorption of light in a magnetic field. The 
former of these subjects is also dealt with by O. M. 
Corbino. The properties of caoutchouc have been investi- 
gated by O. M. Corbino and F. Canizzaro, with regard to 
the variations of its dielectric constants due to traction ; 
while M. Cantone has studied the traction and the accom- 
panying phenomena of hysteresis from a mechanical point 
of view, applying his results to the determination of 
“Poisson’s ratio.” The velocity of Hertzian waves 
forms the subject of a paper by V. Boccara and A. 
Gandolfi, while Murani proves, contrary to the assertion 
of Le Royer and Van Berchem, that a coherer is not 
adapted to exhibit the maximum and minimum points 
of stationary Hertzian waves. In thermo-electricity, we 
have P. Straneo’s papers on the temperature of a 
bimetallic conductor, and on the simultaneous deter- 
mination of thermal and electric conductivities of metals. 
In electricity proper, we may refer to Grassi’s calculation 
of the dimensions of induction in a continuous current 
dynamo, and his note on the work of magnetisation in an 
open cycle; A. Dina’s application of aluminium to 
transform alternating into continuous currents ; F. Lori’s 
studies on the capacity of condensers; and A. Roiti’s 
paper on the two discharges obtainable from one con- 
denser. Of thermodynamical interest are G. Bruni’s 
series of papers on certain solid solutions, and on the 
equilibrium of amorphous mixtures, and of systems of 
two and three components with a liquid phase. C. De) 
Lungo deals with the density of liquids and saturated 
vapours considered asa function of the temperature. 
In chemistry, a long series of quantitative and quali- 
tative analyses have been conducted by Oghialoro, in 
conjunction with O. Forte and G. Cabella, on the waters 
of the baths of Belliazzi in the island of Ischia. 
Menozzi, experimenting on the behaviour of certain 
organic nitrates in contact with the earth, has shown 
that hippuric acid is not absorbed or decomposed by the 
constituents of ordinary ‘earth, though certain salts of 
this acid, similarly treated, undergo transformation. A. 
