180 
38. The size of these atoms must be considered as almost 
inconceivably, but not immeasurably, minute. M. Gaudin, who 
was rather specially adapted to abstract calculations,* published 
in 1873 this approximation. I must premise (for though every 
scholar in Professor Huxley's new Sunday school will be 
familiar with the fact, I have myself to resort to books for the 
exact figures) that a metref is equal to 39*37079 inches, and we 
try to think in French and translate our ideas into English in 
order to grasp the following calculation. I have before me 
the metre on one side, and the yard on the other, of a certain 
whalebone scale which is always on my table; but nevertheless 
I confess that I think in English, and cannot help an effort of 
thought to realise the relation which a millimetre bears to the 
English conception. It is 0*003280825 of a foot. I look 
at the scale, to which I again refer, to fix my idea; for I have 
next to divide the millimetre into a thousand parts, which has 
been perfectly done by mechanical means, and a scale formed 
in proportion. This being placed under the microscope, and 
covered with a drop of water containing infusoria, has enabled 
observers to compare the small infusory animalcules which dart 
about and sometimes rest on the surface of the scale. It has 
been ascertained that they are not larger than one of these 
divisions. 
39. At this degree of enlargement no detail can be perceived. 
The infusoria resemble small globules, but the nature of their 
movements, jerking, angular, and frequently retrograde, shows 
that we have before us small creatures endowed with spon- 
taneous movement, and consequently provided with means of 
locomotion such as muscles and cilia, or other appendages. 
40. M. Gaudin imagines one of these little entities enlarged 
to the diameter of one metre, and then gives us a fancy sketch 
of the creature, and also of a small portion of one of its cilia, 
enlarged to about 45 millimetres in length, in which he shows 
the imaginary building up of the structure by molecules of 
an organic nature represented as one millimetre in diameter. 
These molecules would be of the nature of albumen, and would 
bear about the same relation to the ultimate atoms as a basket- 
ful of grapes would to a single grape. J Chemical considerations 
too abstract to enter into in this paper make it probable that 
* As Calculateur du Bureau des Longitudes and Laureat de l’Academie 
des Sciences. 
t “ The ten-millionth part of the distance from the equator to the pole, as 
ascertained (?) by actual measurement of an arc of the meridian.” 
% Appendix B. 
