124 
NATURE 
[| DECEMBER 10, 1896 
ledge of chemistry to comprehend such a list of names 
and formule as is contained in the foregoing quotation. 
A book constructed on educational lines should not so 
readily run into details, and should never do so without 
sufficient explanatory text. 
Taking the book generally, it is better than many 
others of its class, but little more can be said for it. 
Every geologist will, however, endorse the prefatory 
remark that ‘no text-book, however large, can impart 
an adequate knowledge of geology unless supplemented 
and controlled by actual contact with the facts of nature.” 
Annual Report of the Geological Survey of Canada. 
Newseries. Vol. vii. 1894. (Ottawa: S. E. Dawson, 
1896.) 
Tus large volume of over 1200 pages contains, in 
addition to the Summary Reports of the operations of 
the Survey for 1894, seven detailed reports on certain 
portions of the Dominion, and is accompanied by eleven 
geological maps. 
The Summary Report shows that geological work is 
being carried on by the large staff-of the Survey in every 
part of the Dominion. Especial mention is made of the 
trial borings now being put down at Athabasca Landing 
in the North-west Territories, where there is good reason 
to believe large supplies of oil will be obtained from the 
Devonian rocks at a depth of about 1500 feet. An 
account is also given of the recent advances in the 
development of the mining industry of British Columbia, 
where of late years such extensive mineral deposits have 
been discovered, as well as of the explorations in the 
Labrador peninsula carried out by Mr. Low, who has 
discovered in this inhospitable region deposits of iron 
ore which are believed to surpass in size any that have 
hitherto been discovered in North America. 
Of the special reports, two deal with British Columbia : 
one, by Dr. G. M. Dawson, containing a description of a 
portion of the interior plateau of that provincein the Kam- 
loops district ; and the other, by Mr. R. G. McConnell, 
giving an account of the explorations of the Finlay and 
Omineca Rivers. These are followed by a report on the 
country about Red Lake, in Keewatin, by Mr. Dowling. 
The fourth report is by Dr. R. H. Ells and Dr. F. D, 
Adams, on a portion of the province of Quebec, com- 
prising the island of Montreal and a part of the eastern 
townships to the south and east. Mr. Chalmers then 
describes the superficial geology of the provinces of New 
Brunswick, Nova Scotia, and Prince Edward Island ; 
while, in the concluding reports, Dr. Hoffmann and Mr. 
Ingall treat of the chemical work of the Survey and the 
mineral statistics of the Dominion respectively. Dr. 
Dawson’s report contains an excellent description of the 
interior plateau of British Columbia from a geological 
and geographical standpoint. The very extensive de- 
velopment of the Cambrian in this part of the Dominion 
is noted, as well as the continued volcanic activity from 
Cambrian to recent times, the volcanic materials, at a 
very modest computation, having a thickness of 20,000 
feet. 
Poems of George John Romanes. Pp. xvi+108. (London: 
Longmans, Green, and Co., 1896.) 
THIS small volume consists of a selection from the poems 
of the late Mr. George John Romanes. It contains two 
long poems entitled “A Memorial Poem to Charles 
Darwin,” and “A Tale of the Sea.” Both are fine and 
of a striking quality. Sonnets form the rest of the book, 
and in many of these the naturalist, as well as the poet, is 
revealed to us by the accurate descriptions of nature, 
and the many references to objects and phenomena con- 
nected with science. We may add that Mr. T. Herbert 
Warren, President of Magdalen College, Oxford, has 
written the introduction, in which he gives a short 
biographical sketch of the author. 
NO. 1415, VOL. 55] 
LETTERS TO THE EDITOR. 
[The Editor does not hold himself responsible for opinions ex- 
pressed 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 ts taken of anonymous communications. | 
The Pound as a Force, and the Expression of Concrete 
Quantities generally. 
Wuar is Prof. John Perry tilting at in his educational tirade 
on page 50 of your issue for November 19? To judge from a 
friendly post-card asking me to reply, he seems to imagine that 
he is attacking physicists ; but apart from this private informa- 
tion I should have imagined that he had in his mind a nearly 
extinct type of Cambridge text-book, and some—I do not know 
how many—belated schoolmasters. 
Let me assure him, speaking no doubt for others but of most 
knowledge for myself, that if any student of mine could only 
express force in poundals and energy in foot-poundals I should 
be as disgusted as he himself. 
One of the first things a student of physics has to learn is that 
no numerical exercise is fully worked out until it is expressed in 
units to which he and others are accustomed, and of which they 
can ‘‘ feel” the magnitude. As an intermediate step such an 
expression as 10’ F.P.S. or C.G.S. units is legitimate enough, but 
the final answer should be expressed in hours, or days, or other 
appropriate unit, if time is the subject ; in miles, or millimetres, 
or inches, if it be a length; in hundredweights, or tons, or 
grammes, or pounds weight, if it be a force; and in ergs, or 
foot-pounds, or kilogramme-metres, or Joules, or even in kilo- 
watt-hours, if energy be the quantity under consideration, 
An educated student speaking to a workman should use the 
colloquial unit of the shire in which the works are situated ; in 
addressing a foreign correspondent (if orders ever reach this 
country now from Germany, for instance), he should employ a 
less insular and more international system ; he should, in fact, 
have no difficulty in making a specification in any conventional 
system of units to which he has the key. 
Prof. Perry asks us to limit ourselves to the C.G.S. system on 
the one hand, and to the British gravitational system on the 
other; with those he thinks we can jog along, but with any 
others we are liable to make mistakes. Does he call that 
education? If this is the type of ‘‘ finished engineering student ” 
he issaccustomed to, no wonder they ‘* cannot get into works 
without paying high premiums.”  (Parenthetically I wonder 
what premium the Hopkinsons paid in order to be taken into 
works.) Surely he would not say to a youth training asa banker, 
“* despise all ¢ha/ers and marks as trumpery, let us have nothing 
but good English pounds, and then we shall know where we 
are, and make no mistakes.” 
Ab, but, he will say, these units are appropriate to different 
countries, and you must be able to adapt yourself to the coinage 
in travelling. Even so! Yet he would seek to limit the 
physicist, whose range of travel is as wide as the universe. Has 
he forgotten the variety of subjects with which physical science 
is concerned? Sometimes there is astronomical energy to be 
expressed, sometimes thermal, sometimes chemical energy, and 
sometimes electrical. Would he be content that his educated 
engineer should be able to express these in nothing but a unit 
appropriate to the pumping of water out of a mine? When an 
engineer sees the expression 4 72" (which, by the way, he 
seldom does see ; it is generally wv*/2¢in his books, as if gravity 
were concerned in every transaction of the universe), he is not to 
think of it straight as momentum multiplied by velocity, or even 
as inertia multiplied by the square of a velocity, or as energy in 
any of its protean forms; he is to think of it as a number of 
foot-pounds. He cannot receive the data in any units whatever 
and bring out the answer in any other units whatever, one set for 
the French motor car driver, and another set for the owner, and 
another for the electrician ; no, but he is to say, I must first have 
the mass given me in pounds, or I may make a mistake; then I 
must divide the number of pounds by a mystic number, viz. 
32°18, in order to bring them to the particular kind of practical 
unit of inertia which my revered instructor so highly prized ; 
and then I must be told the number of feet per second contained 
in the velocity (I should be confused by a specification in tele- 
graph posts per minute or kilometres an hour); after that I can 
do the arithmetic quite nicely, and I remember that the answer 
always comes out in foot-pounds, which gives no trouble to any 
one; thus shall my employer not suspect me of being college- 
