[i28o] 
The whole procefs, upon my oft repeated experiments, 
was as followeth. 
Thefe Shells^being harder then nioft of other kinds, are 
to be broken with a fmart ttroak of a hammer, on a plate 
of Iron, or firm piece of Timber, (with their mouths 
downwards) fo as not to crufhthe body of the Fifli with- 
in : the broken pieces being pickt off, there will appear a 
white Vein, lying tranfverlly in a little furrow or cleft, 
next to the head of theFifh, which muft be digg'd out 
with the ftiff point of the Horfe hair pencill, being mada 
ihort and tapering; which muft be fo formed, by rea- 
fon of the vikous clamminefs of that white Liquor in 
/ ^ the Vein, that fo by its fliffnefs, it may drive in the 
matter into the fineLinnen, or white Silk ^ which (M 
though 1 have not yet tryed itj will (1 thinkj be better 
then on Linnen^ and make the colour appear more 
bright and vivid by its refledion. 
The Letters, figures> or what elfe fliall be made on 
the Linnen or Silk, fas much forced in, as it can be by 
the pencillj will prefently appear of a pleafant light 
, green colour s and^' if placed in thcSuriy will change m- 
to the following colours ,* i. e. if in Winter, about noon, 
if in the Summer, an hour or two after Sun rifing, and 
fo much before letting, (for in the heat of the day, ia 
Summer, the colours will come onfo faft, that the fuc- 
ceflion of each colour, will Icarce be diftinguifht 5 ) next 
to the firft light green, it will appear of a deep green ; and 
in few minutes change into a full Sea-green s after which^ 
in a few minutes more, it will alter into a Watchet blew 
from that, in a little time more, it will he oisL Purphjh 
red : after which, lying an hour or two, (fuppofing the 
Sun ftiil fhining) it will be of a very deep Purple red^ 
beyond which the Sun can do no more. 
Note,that thefe changes are made fafter or flowers- 
according to the degrees of the Suns heat. 
But then the lait and moft beautifuU colour, ("after wafh- 
