* naceés. 
290 
LETTERS TO THE. EDITOR. 
[The Editor does not hold himself responsible for 
‘opinions expressed by his correspondents. Neither 
can he undertake to return, or to correspond with 
the writers of, rejected manuscripts intended for 
this or any other part of Nature. No notice is 
taken of anonymous communications.] 
Extrusion of Columnar Ice-Crystals from Moist Earth. 
Tue phenomenon described by Mr. Larkman 
(Nature, December 7, p. 269) was noted and studied 
by Prof. James Thomson in 1864 and later: see notes 
collected in his ‘‘ Papers on Physics and Engineering,” 
1912, pp. 269-71. Rather than freeze on the moist 
earth below, the water prefers to push up the load 
above it so as to be free to form a homogeneous mass 
of ice outside, columns of ice being thus gradually 
extruded. Prof. Thomson regarded the phenomenon 
as an illustration of his principle of thermodynamical 
interaction between congelation and stress or other 
physical circumstances of the medium, which later 
became widely extended and defined in Willard Gibbs’s 
classical work. See also G. F. Becker and A. L. Day 
“On the Linear Force of Growing Crystals,’’ Journal 
of Geology, May, 1916. eo) 
Cambridge, December 8. 
The Name ‘‘ Linethwaite.’’ 
In the review of ‘Cleator and Cleator Moor” in 
Nature of November 16 the interpretation of Line- 
thwaite as flax-field (Lin+thveit) is taken as inevit- 
able because of the contiguity.of a flax-mill. But 
history, which cannot be ignored in explaining place- 
names, does not agree with this solution of the word. 
The flax-mill has been on this site only about a 
century. On the exact site of the flax-mill a hundred 
years ago there stood six conical iron-smelting fur- 
But the field name Linethwaite has been here 
for hundreds of years. Something, therefore, may be 
said for Lin=Linde, or lime-tree; thwaite=a clear- 
ing: the clearing in the lime-trees. The whole dis- 
trict was once forest, and, from time to time, it has 
been denuded of its timber. The process is going on 
at the present time. CESAR CAINE. 
The Vicarage, Cleator. 
Ir is unsafe to dogmatise about place-names, and, 
if I have appeared to do so in the instance of 
Linethwaite, I must plead in mitigation that the 
suggestion in Mr. Caine’s statement.that here is “ the 
oldest flax-spinning mill in the country, perhaps in 
the world,” was irresistible, especially. as the whole 
of the district in question was long in Scandinavian 
occupation. On the other hand, it is extremely im- 
probable that the lime- or linden-tree ever grew in the 
forests of northern England. ,Botanists are not unani- 
mous as to whether any species of lime is a true 
native of the United Kingdom. Even those who 
admit the small-leaved lime (Tilia cordata) to the 
British list recognise it as indigenous only in the 
southern and west midland English counties. Mr. 
Clement Reid seems to have been unable to identify 
fossil remains of this tree, and Mr. H. J. Elwes 
observes that ‘tit seems hardly possible that a native 
tree should have lost its power of reproduction by 
seed in a climate where it succeeds so well even as 
far north as Ross-shire. In the north of France self- 
sown seedling limes are not uncommon” (‘Trees of 
Great Britain and Ireland,’’ vii., 1659). 
Your REvIEWER. 
NO. 2459, VOL. 98] 
NATURE 
[DECEMBER 14, 1916 
FOOD AND WORK. 'f 
UCH of what we know &bout our food has. 
been derived from empiric _ experience 
handed down to us for ages. With the know- 
ledge so acquired the human race, under normal 
conditions, got along comparatively well. 
sequence, little attention was given to the scientific 
investigation of food problems until within the last 
half-century. . Even now the lack of knowledge 
amongst well-educated people of the composition _ 
of foods and their relative nutritive values.may 
not inaptly be compared with that which prevailed 
in respect to fresh air and ventilation before the 
discovery of oxygen and its use in breathing.. It 
is not the purpose of this article to trace the 
various steps by which the gaps in our knowledge 
of food requirements have. been filled. But one 
important discovery of no distant date deserves. 
mention, namely, that each of our foods has its 
own particular value in respect to the production 
or output of work by the human body. - A con- 
sideration of this aspect of food problems is nowa- 
days of vital consequence to a people, which for 
the most part is at work to maintain its national 
existence. ‘ 
But before referring to the energy-value of 
foods it should be remembered that the human 
body, in common with that of every living being, 
suffers. continuous loss every day, due partly to 
wear-and-tear of its structure, partly to the per- 
formance of work, and partly to the production 
of heat for maintaining body warmth.. This loss 
is made good by food, which therefore has several 
functions to fulfil, namely, to supply material for 
structural repair and in early life for growth, to 
provide energy for the performance of work, and, 
lastly, to furnish fuel for the maintenance of heat- 
Foodstuffs. 
If an ordinary suitable diet be examined it will 
be found to contain certain classes of substances 
known as “foodstuffs,” which have been proved 
to be necessary for nutrition. The first of these 
is exemplified by the lean of meat, .the white of 
egg, the casein of milk, the gluten of flour. These 
are the proteins or albuminous foodstuffs, 
and it is only from one or other of these that 
nitrogen can be obtained to nourish the animal 
body. A certain amount of this class of food is 
therefore indispensable, and cannot be replaced 
by any other. But proteins are not all equally 
valuable. Some, such as gelatin, can supplement 
other proteins in supplying nitrogen, but by them- 
selves are unable to sustain life; they are “in- 
adequate” proteins. Others, such as the gliadin 
of wheat and the legumin of peas, are “adequate ” 
to provide for maintenance, for energy, and for 
heat formation, but not for growth. Still others, 
such as the casein of milk and the glutenin of flour, 
are adequate for all these purposes, and for growth 
as well. Inadequate proteins lack one or more 
ingredients indispensable for nutrition. It is de- 
sirable, therefore, to vary the diet in order to 
secure a sufficient amount of adequate proteins. 
The second class of nutrient substances com- 
In con-_ 
