The Locomotive - Lighthouse Survival Blog

1893.
j
THE LOCOMOTIVE. ^94
A SHOUT time ago we published a notice of Mr. Edward P. Thompson's Ilmc to
Mnlr Iiirinttoni*. 3Ir. Thompson now writes to us as follows: — " In your review of my
book on How to Make Ini'eiitionn, you enter a certain criticism. I am willing to concede
to the editor that the scientific facts are not stated as accurately as might be, and this
purposel}-. My object is the use of terse sentences giving to inventors (wlio are as a
class quick of perception) the gist of facts; the leading idea conveyed, if the fact were
stated with all its surroundings. For example, instead of stating that water has its
greatest density at four degrees upon a certain tliennometer, at a certain geographical
level, at a certain degree of purity, etc., etc., I would ])refer to convey the main idea
somewhat thus: — From about four degrees above the freezing point of water, the same
expands, whether heated or cooled. When a fact is stated in some such language, it is
easily remembered, and has a certain suggestiveness about it in behalf of the inventive
mind." ^
Now we had no idea of criticising the terseness or simplicity of Mr. Thompson's
diction. What we objected to was the obscurity of some of his passages, and the
erroneous statements that he has occasionally given as facts. For instance, on page 33 he
says, "Water vapor in contact with red-hot material is decomposed into hydrogen and
oxygen, which are combustible, relatively." We consider this sentence obscure, because
we can't make out what the latter part of it means. Again, on page 40 we read that
" What is true of light is true of heat, because light is usually heat; but what is true of
heat is not necessarily true of light, because heat exists without light." There is some-
thing elusive about this sentence. AVe have worked hard over it, but we can't seem to
surround the idea it is intended to convey. On page 41 he says that "A gas will pa.ss
through platinum at as high temperature as through porous earthenware, but not to such
a degree.'' Now we should like to know, just for the gratification of our editorial
curiosity, what that sentence means. Maybe the author knows, but we find it inscrutable.
Having illustrated what we mean by calling Mr. Thompson's style obscure, we pro-
ceed to quote two or three erroneous statements, in order that the reader may judge
whether or not our criticism was justifiable. On page 36 he says that sound "moves
faster and faster from the source until a certain maximum is obtained." We should like
to be referred to the experiments, or equations, on which this statement is based. On
page 39 we read that " in solids the distance between the molecules is less than in liquids,
and less yet than in gases." This is sometimes true, and sometimes not. In a substance
that contracts when it melts, the molecules are furtiier apart in the solid form of the
substance than they are in the liquid form of it. On page 40 it is implied that the
temperature of a body is proportional " to the rate of vibration of the molecules." This
is not in accordance with the kinetic theory of gases, and unless Mr. Thompson is
prepared to overthrow that theory, he must admit that the passage cited is erroneous.
Again, on page 43 it is said that "the vapors of liquids relatively insoluble produce
double the pressure of either." This does not accord with Dalton's law, and in fact it
refutes itself; for it implies that at a given temperature the vapor pressure of all
mutvially insoluble liquids is the same; and, as everyone knows, this is not the fact.
Again, on page 44 we read that " water boils in glass vessels at 106° C, and in metal
vessels at 100°. A piece of metal placed in the glass vessel makes the water boil at 100°."
This would be an extraordinary fact, if it were a fact, which unfortunately it is not. On
page 46 it is said that light comes to us from the sun in about eight seconds. The true
time is about eight minvtes.
We have said enough, perhaps, to justify our previous critical remarks, and we trust
Mr. Thompson will not feel hurt because we have not changed our opinion of his book.
It is not at all easy to produce such a work as his, and have it free from errors, and we
trust that in future editions he will see to it that the obscurities and inaccuracies in his
book are removed. It is only fair to him to say that we found the book in question to
We criticised nothinar but the scientific end of it.