'' ( a }5 ) 
I (hall add next a word or two concerning Marine 
Rain-bows, which I obferved after a great Terapeft off 
of the Cape of Good-Hope. The Sea was then very much 
toffed, and the Wind carrying off the tops of the Waves, 
made a kind of Rain, in which the Rays of the Sun 
painted the Colours of a Rain- bow. It is true the com' 
mon Iris has this advantage over ours, that its Colours 
are more lively, diftinft, and of longer Extent. In the 
Marine Iris we could diftinguifla only two Colours, viz. 
a dark Yellow on that fide next the Sun, and a pale 
Green on the oppofite fide : The other Colours were too 
faint to be diftinguifii’d; But in recompence for this, 
thele Iris’s are in a greater Number ; oue may fee 20 or 
30 of ’em together 3 they appear at Noon-day, and in 
a Pofition oppofite to that of the common Rain-bow, 
that is to fay, their Curve is turned as it were towards 
the bottom of the Sea. Tho’ in thefe long Voyages 
one fees nothing but Water and Sky, yet each of ’em 
affords fuch Wonders in Nature, as may well employ 
the time of thofe that have Knowledge enough to dis- 
cover them-- 
Laftly, to put an end to thefe Obfervations upon 
Light, I (hall add only one more, concerning Exhala- 
tions in the Night, that form in the Air a long Tra& of 
Light. Thefe Exhalations make a Tra£fc of Light much 
larger in the Indies than they do in Europe. I have feen 
two or three that I fhould have taken for real Rockets : 
They appear’d near the Earth, and caff a Light like 
that of the Moon Come Days after her Change. They 
fall {lowly, and in falling make a Curve Line 3 efpeci- 
ally one which I faw on the main Ocean, at a great di- 
ftance off at Sea, on the Coaft of Malabar. I am, &c. 
De BOVRZES . 
H h 2 
XXIV. A 
