220 
apply the name of Geber is cited, through Avicenna’s 
“De Anima ”’ (the phrase is given by Hoefer, i. 329, as 
Bacon’s), which work is, naturally, condemned by 
Lippmann, on quite inadequate grounds, as “ pseudo- 
graphisch.”’ Thatit differs in style from the “Canon”’ 
is probably correct, but Newton’s “ Daniel and the 
Apocalypse ’’ differs in style from the “ Principia.”’ 
Avicenna’s ‘‘ De Anima’’ was condemned as spurious 
by Dr. James in his ‘‘ Medical Dictionary ’’ (London, 
1743, vol. i, unpaged). The quotation in Avicenna 
is not to be found in the Latin works of Geber. 
According to Berthelot the ‘‘ Liber Septuaginta’’ 
(the Latin MS. of which was noted by Hoefer, whose 
valuable pioneer work has been considerably under- 
estimated) is entirely different in style and content 
from the Latin Geber, although he attributes it, on 
what seem insufficient grounds, to Jabir. There 
are some strikingly similar passages in the above 
work and in the Latin Geber, though I do not assert 
that they had the same author. 
For some years I have asserted in my lectures 
that the criticisms of Berthelot were unsatisfactory. 
There are many other reasons why the arguments 
of Berthelot should be rejected and a new start 
made. Mr. Holmyard inclines to the original view 
that the Arabic Jabir and the Latin Geber are one ; 
my own view, which like his is still hypothetical, is 
that a Greek, Syriac, or Hebrew MS. may be as 
likely to be the original source as an Arabic one. 
The details of the life of Geber are very contradictory, 
but he is said to have been “‘ a Christian who after- 
wards became a Mohammedan,’’ or “of Tarsus.”’ 
This is suggestive. 
The ‘‘Summa perfectionis’’ is probably the earliest 
Latin work of the group attributed to Geber. It 
differs only little from the Greek writings of Alex- 
andrine authors in its ideas, and the doctrines it 
teaches do not seem to represent that remarkable 
advance which is held to throw doubt on its early date. 
The ‘“‘Testamentum”’ referred to by Mr. Holmyard 
differs in content and outlook from the ‘‘Summa”’; it 
does not appear in the earliest printed edition of 
Geber’s works (British Museum, catalogued as 
possibly printed at Venice in 1475, but I am informed 
by the authorities in the Incunabula Department 
it was probably printed at Rome not before 
1480-1490). The ‘‘Testamentum”’ first appeared 
in the Vatican edition (? 1525; the 1480 was also 
a Vatican edition; Kopp, Hoefer, and Berthelot 
have been confused by editions of Geber which they 
have not seen). The‘ Liber de investigatione ’’ may be 
a compilation by some later writer. The ‘‘ Alchimia 
Geberi,’”’ of which Kopp, Hoefer, and Berthelot 
speak, is not a separate work, but merely an edition 
of Geber’s works. As Mr. Holmyard seems to have 
gone some distance in another direction, I thought 
it useful to state briefly what conclusions I have 
reached; the detailed justification of these would 
take up far too much space. The ‘“‘ pseudographic ”’ 
school, however, do not seem to have made out their 
case. J. R. PARTINGTON. 
East London College (University of London), 
Mile End Road, E.1. 

The Stoat’s Winter Pelage. 
A FRIENDLY stoat, which has made our flower- 
garden and rockery his hunting-ground for mice 
and voles during the last three years, has donned 
his winter livery of ermine, and become very con- 
spicuous—a _snow-white little athlete—amid the 
greenery of the present exceedingly green winter. 
This seasonal change of the stoat’s brown summer 
pelage to creamy white is regulated, not by winter 
NO. 2781, VOU. 1It| 
NATURE 



[ FEBRUARY 17, 1923 
temperature, but by latitude. Invariable in the 
stoats of the Scottish Highlands, nearly so in those 
of the Scottish Lowlands, it becomes gradually less 
frequent towards the English Midlands; until in 
the southern counties a complete change of hue is 
exceedingly rare. This change is not due to the 
growth of a new coat ; it is the old fur that becomes 
white. Nor is prevailing temperature the cause of 
change. Here, on the westérn Scottish seaboard, 
winter is usually very mild; snow seldom falls and 
still more seldom lies. Clianthus puniceus, from 
the north island of New Zealand, and Abutilon 
megapotamicum, from Brazil, have been flowering 
profusely on walls in the open all through this 
winter ; yet our stoats regularly assume the protec- 
tive winter garb of circum-polar animals ; 
in Warwickshire and Leicestershire, where the average 
winter temperature is far more severe, a complete 
change in the stoat’s pelage very rarely occurs. 
May we not recognise in this a heritage from the 
last ice age ? So long as the land so far south as 
Herts lay under the ice, stoats in the Thames valley 
and south thereof must have worn the ermine pelage 
—at least in winter, and so did those which followed 
the ice in its northward retreat. But’some thousands 
of temperate seasons have enabled the race of stoats 
that remained in the southern counties to dispense 
gradually with a costume which has become the very 
reverse of a protective disguise. 
A few thousand years more and it may be as 
difficult to find a white ermine in Caithness as it is 
now in Cornwall ! HERBERT MAXWELL. 
Monreith, Whauphill, 
Wigtownshire. 

Stirling’s Theorem. 
For very large values of , Stirling’s theorem, 
. Se | sa 
Ue ile 
nre-™ Jn Jam, 
reduces in its logarithmic form to 
nlogn —n =log | x. 
It is in this form that the formula is required in 
Planck's radiation theory. Wanting to use this 
formula, and unwilling to make my students go 
through the proof of Stirling’s theorem as given, 
for example, in Chrystal’s ‘‘ Algebra,” I thought of 
the following deduction, and should like to know if it 
is sound or if it has been given before. 
When dn =1 
log nm =--— log |” 
and since is to be very large the value of du is an 
infinitesimal. Therefore we may say 
log n dn =d log | 
«. Jlogn dn =J d (log | 7) 
-. nlogn -n =log |x, 
which is the form required. JOHN SATTERLY. 
University of Toronto, 
Toronto, Canada, 
January T. 

Stonehenge: Concerning the Four Stations. 
Jusr within the surrounding earthwork of Stone- 
henge there are two stones symmetrically placed 
with reference to each other on opposite sides of the 
centre. There are also two low earth heaps or 
mounds in corresponding complementary or reversed 
while © 
3 
