FACTS AND OBSERVATIONS. 
407 
developed, as is the case with the spinal axis of the verte¬ 
brate. Such an examination makes us esteem lightly such 
generalisation of the mere external form of the nervous 
system as that made by Audouin and Milne-Edwards in the 
Crustacea, as being only a prelude to a more natural and 
scientific classification. 
The Phenomena of Attraction and Adhesion, 
as exhibited in solid bodies, films, liquid globules, &c., have 
been lately investigated by Mr. Richard Norris. Mr. Norris 
observes that solid bodies floating on liquids modify the 
figure of the surface of the liquid; pieces of tinfoil or greased 
bodies depress the liquid around them, whilst other bodies ele¬ 
vate it, giving rise to small mounds of liquid bounded by con¬ 
cave lines; likes attract likes, and repel unlikes, &c. He states 
that the following experiments are arranged to show that 
these effects of attraction are not peculiar to floating bodies, 
and that the only requirement is that the liquid should 
be associated with the bodies in which the movement occurs. 
1. Let two balls of sealing-wax, or other material of greater 
specific gravity than water, be suspended by hairs in such a 
manner that they will both be partially immersed in water to 
an equal extent, the points of suspension being at a little 
distance apart, and the suspending hairs consequently 
parallel. When brought within the proper range they will 
attract each other in the same manner as the floating bodies. 
In doing so they necessarily describe a small arc of a circle, 
of which the suspending hair is the radius, and have, therefore, 
not simply moved towards each other in a horizontal line, 
but have been raised to a higher level. 3. Suspend movably, 
by means of a thread passing over a pulley and a counter¬ 
balancing weight, a horizontal cork disc, from the under sur¬ 
face of which a drop of water is hanging. On a support 
beneath, formed by three upright pins, place a small piece of 
paper or thin glass, on the surface of which there is also a 
drop of water. On depressing the disc until the two drops 
of water touch each other, the paper or plate will be instantly 
drawn up to it; or, if the plate at the bottom be heavier 
than the disc, the latter will be drawn down. 6. When a 
soap bubble is allowed to fall on an irregular surface, such 
as a piece of lint or flannel, it maintains its spherical shape; 
but if a smooth surface, such as a sheet of glass, be brought 
into slight contact with it, the wall of the bubble will be im¬ 
mediately attracted and flattened out upon it. In like 
manner, when two bubbles come in contact by their convex 
surfaces and cohere, the cohering surfaces become flattened, 
and the bubbles in a group cohere by plain surfaces. 
