225 
tion.” This is so obviously an abuse of language that it needs 
no further comment. 
21. Mr. S. Baring- Go uld, in a very unsuccessful attempt to 
elucidate dynamical principles,* has defined force to be that 
which produces or resists motion ; and further on we meet with 
confusion worse confounded, for not only “ light, colour, heat, 
electricity,” but “dimension . . . solidity, liquefaction, vapori- 
sation,” are modes or modifications of force: how “colour” 
and “ dimension” are to “produce or resist motion” it is not 
easy to apprehend. An indefinite number of such misapplica- 
tions of the term “ force ” might be further adduced, but 
enough has been stated to show the very loose manner in which 
that term has been used by writers on physical subjects. 
22. The terms force and energy are frequently used indis- 
criminately in common parlance ; “ thus, it is common to 
speak of the force of the powder, and the force of 
the shot : the powder has force, but the shot only energy. 
Again, the terms f force of inertia/ ‘ force of percussion/ 
‘ centrifugal force/ have been frequently but erroneously em- 
ployed. Inertia is simply the negation or non-existence of any 
disturbing energy. In cases of percussion, the energy of the 
striking body may be more or less imparted to the body struck, 
either with or without the intervention of the force of elasticity. 
This may be shown by means of two suspended ivory balls. If 
a little bit of putty be placed on the point of impact of one ball 
at rest, and the other be raised and allowed to impinge directly 
upon it, they will swing together to half the height that the one 
ball descended from, because the energy acquired by the 
descending ball is just sufficient to raise double the mass to 
half the height. But if the elasticity of the balls be allowed 
to come into play by the removal of the yielding material, then 
the striking ball remains at rest, and that which was struck 
rises very nearly to the height from which the former descended, 
elastic force having in this case imparted to the ball at rest nearly 
the remaining half of the energy of the striking ball. The 
instantaneous transmission of the energy of impact through a 
long row of glass balls in contact may be adduced as a rough 
illustration of the molecular transmission of energy : if the 
first ball of the row be struck, visible motion will be imparted 
to the last only. The term f centrifugal force/ denoting the 
tendency of a revolving body to fly off from its orbit, will in 
all cases be correctly replaced by ‘ centrifugal energy/ ” 
23. In order to maintain a logical accuracy of diction in treat- 
ing the subject of this paper it becomes necessary to consider 
* Origin and Development of Religious Belief \ Part I., chap. I. 
