538 
NATURE 
[APRIL 4, 1907 
answer this*purpose. Whatever the object may have 
been, there can be no doubt as to the tedious. and 
complicated nature of the means employed. 
Before the twenty-first dynasty, the process of em- 
balming resulted in a mummy which was simply a 
skeleton wrapped in a wrinkled covering of shrivelled 
skin. In this dynasty, or at the close of the twen- 
tieth, the process of packing or “ stuffing ’? was intro- 
duced to avoid the shrivelling of the flesh and distor- 
tion of the body which marred the work of the older 
embalmers. The mortal flesh was replaced by sub- 
cutaneous packings of durable material such as mud, 
sand, lime, and sawdust, with occasionally an addition 
of aromatic vegetable substances such as onion. The 
eyes of the great Rameses IV. were replaced by 
onions. After the twenty-first dynasty, the art of em- 
balming declined. Subcutaneous packing was discon- 
tinued, the surface form of the body being restored 
by swathing the limbs and body by an artistic appli- 
cation of bandages; later still all distortion was 
hidden by a free application of pitch and bandage to 
the shrunken trunk and limbs. 
In the course of his investigations, Elliot Smith 
was able to verify certain statements made by Hero- 
dotus and by Diodorus Siculus concerning the methods 
of embalming empleyed by the ancient Egyptians. 
Herodotus describes the extraction of the brain 
through a small opening made on the roof of the 
nasal cavity—a procedure which Greenhill character- 
ised as ‘“‘ amusing and impracticable.’’ It was found 
that all the mummies belonging to the seventeenth 
and later dynasties showed clear evidence of the 
truth of the ancient description; early in last cen- 
tury, T. J. Pettigrew also verified it. In the 
writings of Pettigrew and in Brugsch’s translation 
of the Rhind Papyri, the author of the memoir found 
much that assisted him in re-constructing the details 
of the process used by the embalmers. Broadly 
speaking, there were three stages: (1) the viscera 
were removed from the body through a wound in the 
left flank, the heart being invariably left in the 
trunk; (2) the body was then placed in brine for a 
period of thirty or forty days; the viscera were pre- 
served in a similar medium within the four ‘“ Canopic 
Jars,’’ each of which was dedicated to one of the four 
children of Horus; (3) after removal from the salt 
bath the body, now much shrunken, was packed; 
from the arrangement of the packing, Elliot Smith 
found it possible to tell the exact manner and order 
in which this had been accomplished; it is unneces- 
sary here to mention the details, but one may safely 
state that these ancient embalmers must have had a 
very considerable knowledge of the anatomy of the 
human body. 
The process of packing was finished by returning 
the contents of the four canopic jars to the body 
cavity ; they were arranged in four packages, and were 
usually replaced within the cavity in a certain de- 
finite order. In each package it was the custom to 
enclose the image of one of the four children of Horus 
—‘‘funerary genii,”” as they are named in_ this 
memoir. 
The following statement of Pettigrew is quoted in 
this connection :— 
“To Amset were dedicated the stomach and large 
intestines; to Hapi the small intestines; to Smautf 
(Tuamautef) the lungs and heart; and to Kebhsnuf 
the liver and gall bladder.”’ i 
On this Prof. Elliot Smith makes the following 
commentary :— 
“The examination of a still larger series of mum- 
mies of this period (twenty-first dynasty) has convinced 
me that, in spite of frequent irregularities, a definite 
association was intended—but the guardianship of the 
NO. 1953, VOL. 75] 
various Genii is by no means identical with that sug- 
gested by Pettigrew. Thus the human Amset is 
usually found wrapped up in the liver instead of the 
stomach and large intestines, the ape-headed Hapi is 
usually associated with the left lung rather than the 
small intestines, the Jackal Tuamédutef with the 
stomach . . . and the hawk-headed Kebhsnuf ... in 
the parcel of intestines.”’ 
There are many other points in this memoir which 
are deserving of notice, but enough has been said to 
show its value as a real contribution to our know- 
ledge of the ancient Egyptians. 
ASTRONOMICAL REFRACTION. 
HEN a ray of light passes through a medium 
of uniform density, the path described is a 
straight line. Should this ray meet obliquely another 
medium of different density it is bent or refracted. 
If the second medium is more dense than the first, 
then. the ray as it enters the second medium is re- 
fracted towards the normal, or that line at right 
angles to the tangential plane at the point where the 
ray enters the second medium. 
In the case of astronomical refraction, the light, 
say, from a star, passes through space and then 
penetrates the earth’s atmosphere, a medium which 
is in all parts denser than the space between the star 
and the upper limit of the earth’s atmosphere. By 
the time.the ray reaches the observer it will there- 
fore be considerably bent towards the normal. If 
our atmosphere were homogeneous, that is, if it were 
of equal density throughout, the star’s light would 
pass in a straight line from the point where it first 
penetrated it to the observer’s eye. We know, how- 
ever, that our atmosphere is far from being of 
uniform density, and one has not to climb a moun- 
tain or ascend in a balloon very high before this fact 
is made plain. 
Up to a few years ago little was known with 
certainty about the physical conditions of the upper 
atmosphere, except the broad idea that the air be- 
came less dense the greater the distance from the 
earth’s surface, and that at the same time the 
temperature readings were lower and lower. 
This limited knowledge of our atmospheric con- 
ditions rendered it necessary to make some assump- 
tions as to the law of decrease of density. This was 
imperative, because it was of vital importance to 
astronomers and mariners to know how much the 
ray of light from a celestial object had been bent 
after it had penetrated our aérial envelope. In fact, 
what was required was the difference between the 
apparent and actual direction of the heavenly body 
in the sky. 
The assumption finally made was that the atmo- 
sphere consisted of a series of concentric spherical 
layers the common centre of which was the centre of 
the earth. Each layer was considered of uniform 
density, and these densities or temperatures and re- 
fractive powers all decreased as the surface of the 
earth was left behind, the amount of decrease varying 
in a prescribed way and agreeing in the main with 
the actual, but few, observations made in balloons 
and on mountain tops. On this assumption, then, the 
ray which entered our atmosphere was always meet- 
ing with denser and warmer layers of air, and 
gradually becoming more and more bent as each con- 
secutive layer was passed through. : 
During the course of the last few years very rapid 
strides have been made in investigating the upper air 
by means of manned and unmanned balloons and 
kites carrying meteorological instruments, and eleva- 
