APPENDIX. 889 



then B. freezes while A. radiates this last unit into space. This pro- 

 cess, of course, goes on through the whole group. 



While this loss of temperature is going on there is an accompanying 

 change taking place. The molecules A. and B. (B. more rapidly than 

 A.), in obedience to the universal law of nature, are contracting upon 

 themselves, and B., moreover, in obedience to another and invariable 

 law, is contracting and crystallizing in the direction of A., the surface 

 through which it loses heat And hence we find the two rows of mole- 

 cules B., which in Fig. I. touched each other in the centre of the 

 group, are in Fig. II. drawing away from each other, and are concen- 

 trating and crystallizing in and between molecules A. Molecules A., 

 being still liquid or plastic, yield to the pressure, and allow a different 

 molecular grouping ; so that, although they themselves have obeyed 

 the same invariable law. yet the difference of time at which they have 

 done so has allowed a sufficient number of the molecules B. to be thrust 

 between them, and thus more than make up for their own contraction, 

 and hence the resultant ice-crystal will present a greater superficies 

 than the molecular group of H 2 0, from which it was formerly, and 

 should naturally present a vacuum in its centre. 



As an example of the increase of superficial surface by an alteration 

 of the molecular arrangement, we have only to refer to the common 

 soap bubble. Of course no similarity of production is implied, but 

 the result is the same in a degree. 



So it follows that, if the reasoning is true, the so-called "expansion 

 of ice " cannot be looked upon as a special providence for the little 

 fishes, but must be regarded as another manifestation of the invariable 

 and immutable course of Nature's law. 



April Is/, 1881. 



APPENDIX H. (See page 682.) 



TIDE MEASUREMENTS MADE AT BENNETT ISLAND, 



July, August, 1881. 



July 30, 10.26 

 11.26 



P M. 



12.26 

 1.26 



2.26 



A. M. Feet. Inches. 



3.26 .... 9 

 4.26 ...14 



5.26 . . , 1 11] 



6.26 . . . 2 5\- 



7.26 .... 2 8 

 8.26 ... 2 U 1 



1 Rise of 2 feet, 4^ inches. 



