ocular SpeSfra of Light and Colours. 333 
by temporary paralyfis. The arm drops down after violent 
a£tion, and continues for a time ufelefs ; and it is probable, 
that thofe who have perifhed fuddenly in fwimming, or in 
fcating on the ice, have owed their deaths to the paralyfis, or 
extreme fatigue, which fucceeds every violent and continued 
exertion. 
X. MISCELLANEOUS REMARKS® 
There were fome circumftances occurred in making thefe 
experiments, which were liable to alter the refults of them, 
and which I fhall here mention for the affiftance of others, who 
may with to repeat them. 
I. Of direct and Inver fe fpedlra ext/ling at the fame time ; of 
reciprocal direct fpeEira ; of a combination of dir eld and inverfe 
fpectra V of a fpeldral halo ; rules to pre-determine the colours of 
fpeldra * 
a. When an area, about fix inches fquare, of bright pink 
Indian paper, had been viewed on an area, about a foot fquare, 
of white writing paper, the internal fpeftrum in the clofed eye 
was green, being the reverfe fpedlrum of the pink paper ; and 
the external fpectrum was pink, being the direct fpe<?crum of the 
pink paper. The fame circumftance happened when the in- 
ternal area was white, and external one pink that is, the 
internal fpefilrum was pink, and the external one green. All 
the fame appearances occurred when the pink paper was laid 
on a black hat. 
b. When fix inches fquare of deep violet poliflied paper was 
viewed on a foot fquare of white writing paper, the internal 
fpeftrum 
