NATURE 
357 
THURSDAY, AUGUST 19, 1886 
PHYSICAL HYPOTHESES 
Le Ipotest Fistche. Analizzate da Giannantonio Zanon. 
(Venezia: Lorenzo Tondelli, 1885.) 
ee its sitting of July 17, 1881, the Royal Venetian 
Institute of Sciences proposed as the subject of a 
prize an examination of recent hypotheses regarding the 
causes of luminous, thermal, electrical, and magnetic 
phenomena. The volume now before us is one of seven 
competing treatises produced by the end of March 1883. 
As to the vastness of its scope, and the extent of erudition 
displayed in it, we can fully ratify the sentence of the 
examiners officially deputed to pronounce upon its merits. 
It is an “attack all along the line,” and one conducted 
with no despicable array of mustered forces. The author 
has read and pondered much on the subjects he treats 
of ; he is a mathematician, and is hence alive no less to 
the value of mathematical evidence, than to the worth- 
lessness of a mere hollow show of mathematical formule; 
while the hypotheses he criticises have usually been tried 
by the severe test of a serious endeavour to realise their 
consequences. Many of his objections we at once admit 
to be valid; indeed, no universal explanation of physical 
phenomena has yet been proposed of which the structure 
was not riddled with visible absurdities. The late Prof. 
Challis devoted his considerable abilities and his best 
energies to the elaboration of a hydrodynamical theory of 
the universe, in which physical effects of all kinds were 
referred to forms of pressure of a continuous elastic 
medium. But the suggestion that an indefinite ascending 
series of such media might, after ail, be necessary to 
produce the required results, cannot be looked upon 
otherwise than as a confession of failure. Father Secchi’s 
heroic effort, in his “ Unita delle Forze Fisiche,” to see 
right down to the very bottom of things, was scarcely 
more successful. The reasonings upon which it was 
founded (as our author, among others, rightly points out) 
were vitiated at the root by a misapplication of Poinsot’s 
theorems on the resilience of rotating bodies ; and the 
cosmical machinery put together with such ingenuity, 
and set going with such heedful solicitude, came at once 
to a deadlock. Nor do we anticipate any better results 
from the scheme which Prof. Zanon himself promises to 
expound in a forthcoming work. The glimpses of his 
views afforded in essays already before the public are not 
encouraging. There is absolutely nothing gained in de- 
volving the responsibility of our ignorance upon phrases, 
and taking their obscurity for illumination. If we can 
find no adequate explanation of the activities manifested 
in the wonderful “frame of things,” of which we are at 
once spectators and participators, let us, in the name of 
candour and common-sense, acknowledge our impotence ; 
but let us not imagine that we in any sense repair or 
qualify it by talking of inherent qualities, “virtues,” pro- 
pagated ‘‘influences,” “ molecular tensions,” and the like. 
This would be to fall back into the rut out of which 
Moliére did something to help us with Argan’s famous 
diploma-examination :— 
VOL. XXxIV.—No. 877 
** Mihi a docto doctore 
Domandatur causam et rationem quare 
Opium facit dormire. 
A quoi respondeo, 
Quia est in eo 
Virtus dormitiva, 
Cujus est natura 
Sensus assoupire.” 
Undeniable ; but uninstructive. 
The work we are at present concerned with is divided 
into an historical and a critical section. Of hypotheses 
as to the constitution of matter and the causes of physical 
action, the human mind has in all ages been prolific. 
Their procession, lengthy as that which defiled before 
Bradamante in the grotto of Merlin, is here carefully, and 
as expeditiously as may be, marshalled for our benefit. 
From the aqueous world of Thales to the vortex-atom 
world of Sir William Thomson, we are enabled to trace 
the progress, or rather the vicissitudes, of thought. For 
it is not in this field that the amazing advances of modern 
science have been made. The subject of Prof. Zanon’s 
sketch is, not the onward march of natural investigation, 
but the “stations and retrogradations” of speculative 
physics. More than once, indeed, he is forced to exclaim 
with Horace, “Multa renascentur, que jam cecidere.” 
The incidental inclusion of some fragments of genuine 
scientific theory, legitimately verified by experience, does 
not alter this general character. 
The narrative is disfigured by a few inadvertencies. 
At p. 44, for example, the origination of the wave-theory 
of light is ascribed to Malebranche ; but in the very next 
page, and with better reason, to Hooke, whose “ Micro- 
graphia,” containing the assertion that “light is a very 
short vibrative motion,” propagated in spherical waves of 
agitation through “an homogeneous medium,” appeared 
in 1665, nine years before the first-fruits of Malebranche’s 
meditations were given to the world. At p. 50, Lavoisier’s 
vationale of combustion is inextricably involved with his 
rationale of the decomposition of water; and at p. 118 
the point is strangely missed of Prof. Tyndall’s illustrative 
explanation of the change from the liquid to the gaseous 
state. It is worth while to point out these slips in a 
book representing a large amount of painstaking original 
research, 
No notice is taken in it of Isenkrahe’s recent specula- 
tions concerning the cause of gravity. They belong to 
the same family with those of Le Sage, justly condemned 
as “a mere effort of imagination, defiant alike of the 
dictates of reason and the laws of nature” (p. 229), 
Shelter from molecular bombardment, in one form or the 
other, is the key offered by them to the standing riddle of 
the cosmos. They explain gravity as a fush, not a pull. 
Central forces are replaced by the preponderant external 
impacts of “mundane” or “ ultramundane” particles. 
Such theories write their own sentence. They include 
their own condemnation, For, as M. Isenkrahe with the 
utmost candour points out, the very form of his funda- 
mental equation implies a contradiction of the law that 
gravity varies with mass. It is obeyed only when the 
value of the equation becomes equal to nothing—that is, 
when there is no action of the kind postulated. 
In the critical section of Prof. Zanon’s volume, theories 
of the constitution of matter are examined separately 
from theories of the physical forces. That perplexities 
R 
