' 
April 19, 1883] 
NATURE 
579 
be the footsteps of no other animal than man, and the engravings 
and photographs which accompany the paper leave no doubt on 
the mind of any one who sees them. The most remarkable 
circumstance characterising them is their great size, In one 
case there are thirteen footprints measuring 19 inches in length 
by 8 inches wide at the ball, and 6 inches at the heel. In 
another case the footprints are 21 inches long by 7 inches wide. 
There are others of a smaller size, possibly those of women. 
One track has fourteen footprints 18 inches long. The distance 
between the footprints constituting a ‘‘step” varies from 3 feet 
3 inches to 2 feet 3 inches and 2 feet 8 inches, whilst the distance 
between the consecutive prints of the same foot constituting a 
** pace”’ varies from 6 feet 6 inches to 4 feet 6 inches. In none 
of the footprints of the deposit are the toes or claws of animals 
marked. As regards the beasts, this is probably due to the 
‘*slushy ” state of the mud when the tracks were made. But 
in the case of the human footprints it is probably due to the use 
of some kind of shoe or mocassin. 
I need not say that so far as the geological horizon is con- 
cerned this discovery does not carry the existence of man beyond 
the Quaternary Mammalia, with which it has long been pretty 
clear that he was associated in prehistoric times. Nevertheless 
it is, if confirmed, a highly remarkable discovery, especially as 
connected with the curious intimation so concisely made in the 
Jewish Scriptures, ‘‘And there were giants in those days.” 
Hitherto, so far as I know, the remains of prehistoric man, so 
far as hitherto discovered, have not revealed anything abnormal in 
point of size, It is just possible that the slippery and yielding nature 
of the muddy lacustrine shore on which the tracks were made 
may have partly occasioned the apparent size. ut the photo- 
graphs and engravings exhibit them as very sharp and ‘‘ clean 
cut.” Professional Indian trackers have been employed to ex- 
amine the tracks, and none of them seem to have the smallest 
doubt as to the footprints being human. ARGYLL 
Cannes, April 14 
P.S.—The paper was sent to me by my son, the Governor- 
General of Canada, a few weeks ago. 
“The Ether and its Functions” 
In NATURE, vol. xxvii. pp. 304, 328, is a reprint of a lecture 
delivered by Dr. Oliver Lodge in December 28, 1882, at the 
London Institution, on ‘‘ The Ether and -its Functions.” As 
this happens to be a subject to which I have devoted special 
attention, 1 would beg to offer a few remarks, also as wy name is 
alluded to in the article, 
The repudiation of the assumption of ‘‘action at a distance ” 
in the first part of the lecture, coupled with the ingenious argu- 
ments by which its baselessness is exhibited, will no doubt be 
encouraging to all those who favour the advance of knowledge. 
But that portion of the lecture dealing with the constitution of the 
ether (and which assumes it to be non-molecular) is to my mind 
disappointing, as it looks hke a step backwards to suppose the 
ether to be something essentially different from ordinary matter, 
while on all sides the simple opinion of the ‘‘unity of matter” 
has been making progress. I will quote the passage more 
especially relating to this point, viz. :— 
“As far as we know, it (the ether) appears to be a perfectly 
homogeneous incompressible continuous body, incapable of 
being resolved into simple elements or atoms ; it is in fact con- 
tinuous, not molecular. There is no other body of which we can 
say this, and hence the properties of ether must be somewhat 
different from those of ordinary matter” (p. 305). 
It will be admitted that clearness is a first desideratum in a 
theory, It appears difficult to see how an ‘‘zncompressible” 
body isto transmit waves.* A remark of Maxwell’s in his paper 
“On the Dynamical Theory of Gases” has some bearing on this 
point, viz. : ‘‘ The properties of a body supposed to be a uniform 
plenum [z.e. not molecular] may be affirmed dogmatically, but 
* For it seems apparent that an incompressible, non-molecular, ‘* friction- 
less”’ liquid could not-have wave-energy imparted to it at all, or a hot 
substance could not emit light or heat in such a medium. Moreover let us 
(in a spirit of fair argument) take a representation of one of the most 
commonplace effects in physics, say an explosion of gunpowder. Then the 
assumption of “*action at a distance’”’ being rejected, there is (admittedly) 
no more playful building of castles in the air out of ** force,’’ or no store of 
phantom energy to get the motion (“‘explosion”’) from. ‘The motion there- 
fore must inevitably come from the matter of space, or froma set of particles 
or atoms already in motion in space in their normal state. How is a non- 
molecular, /rictzondess liquid to lay hold (astit were) or act upon the molecules 
of gunpowder and put them in motion? Is not the objection conclusive 
though elementary ? 
cannot be explained mathematically” (Pi. Trans., 1867, 
p- 49). Moreover, it seems hard to reconcile the fact that Sir 
W. Thomson’s theory of the constitution of matter is apparently 
adopted or favoured in the lecture, and yet at the same time the 
molecular or atomic nature of the ether is repudiated. But is 
not Sir W. Thomson’s theory of matter essentially an atomic 
theory? The incompressible fluid outside the vortex atoms can- 
not serve as the ether, or this seems an impossibility. Maxwell, 
for example, remarks in relation to this point, viz.: ‘‘The 
primitive fluid [7.2. the fluid exterior to the atoms] entirely eludes 
our perceptions” ! (see ‘* Encyc. Brit.,” article ‘* Atom,” p. 45). 
The ether, however, does not entirely elude our perceptions, but 
is very distinctly felt in the beating of the waves of light upon 
the eye. It appears, therefore, that if the ether is to affect the 
senses at all it must consist of atoms or molecules (doubtless 
very much smaller than those of gross matter, a difference in 
degree but not a difference in Aizd). It may be noted in passing 
here how often notoriously has the error of mistaking a mere 
difference in degree for a difference in kind or essence been made 
in the history of science, and the correction of this error with 
the correlation and simplication of views attendant on its re- 
moval marks one of the chief stages of our progress. The 
theory of evolution abolished this error in regard to the animal 
world ; its abolition in regard to the universe of matter is equally 
demanded. One satisfaction that Sir W. Thomson’s theory of 
matter brings, consists perhaps in the fact that it does not over- 
throw our old conceptions as to the atomic constitution of matter 
so firmly built up by the able reasoners of the past, including 
Lucretius and Newton—and which has produced such great 
results for science. The Thomsonian view goes rather to con- 
firm the atomic theory and to establish its truth by explaining in 
addition how an atom can be e/as¢zc and yet indestructible. Let us 
not deviate from the well-tried ground of the atomic constitution 
of matter, already won with so much labour, unless we are 
forced to do so, and let us work towards the great generalisation 
of the Unity of Matter and of Energy. 
London, April 
P.S.—My views regarding the Matter of Space (the result of 
many years of thought and study) are contained in various scat- 
tered papers, references to the chief of which may be conve- 
niently given here, viz. Philosophical Magazine, September and 
November, 1877, February, 1878; NATURE, January 15,° 1880 ; 
March 17, 1881; March 20, 1879; Philosophical Magazine, 
August, 1879, November, 1880; April and May, 1880, &c., &c. 
Also a little book, ‘‘ Physics of the Ether” (E. and F. N. Spon), 
was published in 1875 as a first imperfect essay on the subject. 
The above papers include an atomic theory of the ether, capable 
of affording a simple and natural explanation of gravitation 
without the aid of ‘‘ultramundane corpuscules ” [2.e. without the 
supply of any energy or matter at all from outside the bounds 
of the visible universe]. Dr. Lodge seems to admit that his 
premises cannot explain gravitation. But is not the elucidation 
of gravitation (which may be called the primary physical effect 
in the universe) one of the first requirements of any theory of 
the constitution of the Matter of Space? A more concise sum- 
mary of my views (with additions and developments, the work 
of recent years) regarding the relations of the Matter of Space 
to ordinary matter and to the local fluctuating changes taking 
place in the universe, may be found in the forthcoming volume 
of the Zyansactions of the Vienna Academy of Sciences, to which 
they have been communicated by Prof. Ludwig Boltzmann of 
Graz. 
S. TOLVER PRESTON 
““Krao” 
Some two months ago there appeared in NaTuRE (vol. xxvii. 
Pp. 245) certain statements about ‘*Krao,” the Siamese hairy 
child, which with your leave I would venture to correct. Krao’s 
parents are both Siamese, not Laos ; they are both still living 
in this city; neither of them presents any special peculiarity ; 
they have other children still living, and also showing no special 
peculiarities ; Krao, it is true, was not born in Bangkok, but in a 
village between this and the sea, her parents having a little time 
before her birth run away from their master, but coming back 
after the event. Siamese is of course Krao’s native language ; 
1 A clear and able exposition of the relation of Sir W. Thomson’s theory 
of matter to the old-established atomic theory may be found in a paper on 
“The Atomic Theory of Lucretius,” by an anonymous author in the .Vorti 
British Review for March, :868. . A é 
2 This paper includes a corpuscular theory of light consistent with the 
main principles of the undulatory theory—vo? therefore an evzdssion theory. 
