4 Mr. Harvey on the formation 
the moisture was not confined to the small triangular and curvili- 
neal spaces alluded to in the preceding experiment, but was dif- 
fused over the whole surface, excepting the parts in contact with 
the wood. The metallic surface presented therefore a dry portion 
with well defined borders, in the form of the algebraic sign plus ; 
and four triangles of dew, formed of particles, beautifully distinct, 
but undergoing a minute diminution in size, from the edges of the 
paper to the vertices of the triangles, as represented in fig. 2, To 
contemplate these triangular formations of dew to advantage, it 
was necessary to place the eye in a situation to receive the impres- 
sion of the reflected light. In such a position the forms of the tri- 
angles were viewed to great advantage ; the innumerable atoms of 
dew presenting a pleasing contrast to the unsullied figure of the 
cross. 
On the same night a similar surface of gold metallic paper, simi- 
larly circumstanced, presented an appearance as in fig. 3, in some 
degree analagous to that represented for the silver paper im fig. 1. 
The moisture seemed however destitute of that uniformity which 
characterized the particles formed in the last-mentioned diagram, 
although some slight approach to it might be traced, in the forma- 
tion of the irregular patches of dew, in the angular portions of the 
figure. 
On the following night, portions of silvered paper attached to 
triangular and square frames, as denoted by figures 4 and 5, were 
presented to the nocturnal sky. In the former, the beautifully 
minute particles of dew were confined to the equilateral triangular 
surface, not in contact with the frame; the particles however 
seeming to preserve an uniformity of magnitude over the whole 
surface. To the middle of the non-metallic surface of fig. 5, a cir- 
cular piece of wood was attached, of the same thickness as the 
frame ; and during the abundant deposition of dew which took 
place in the course of the night, the moisture was strictly confined 
to the parts of the metallic paper, not in contact with the wood ; 
the small circular portion, although surrounded as it were with an 
atmosphere of moisture, presenting as effectual a -barrier to its 
formation as the external frame. 
