( m ) 
space of* more than two years, at the end of which time the 
animal appeared as healthy as when Inclosed. 
Aht. 'KXJLYll.-^Proceedmgs of the Cambridge Philosophical 
Society. 
Nov. 13. 1820.“— Paper by Dr E* D. Clarke was read. In 
the first part of this paper, Dr Clarke explained, by quotations, 
the difi'erent kinds of pigment used by the ancients in decora- 
ting works of art. He afterwards endeavoured to ascertain, 
on the authority of Pliny, some facts respecting the chemical 
nature of the substances used in such decorations. The paper 
concluded, with the detail of certain experiments which led to 
the discovery of a preparation, which gave to Plaster of Paris 
Casts the effect of the Rosso-antico Marble. 
A notice was read by Professor Lee, Of the Astronomical 
Tables of Mohammed Ibn Ahiheker al Farsi^ two manuscript 
copies of which are preserved in the public library of the Uni- 
versity. The only previous notice which is to be found of this 
work, is given by D’Herbelot, and is in many respects erroneous. 
The Tables are founded on the observations of Al Shirwani, 
the date of which is the year 541 of the Yezdigerd, and claim 
to be much more correct than any which preceded them, though 
it was probably upon some of the earlier ones that the Alphon- 
sine Tables were constructed. After giving a translation of the 
preface, and a list of the contents of the work. Professor Lee 
added a liable of the places of the planets for the year 631 of 
the Yezdigerd, and for the longitude of Sena in Arabia Felix; 
and another of the latitudes and longitudes of a considerable 
number of places which are remarkable in oriental geography. 
Nov. 27. — A paper was read by Dr E. D. Clarke, On a For^ 
motion of Natron^ discovered by Dr Wavell, in the decompo- 
sing stone of the tower of Stoke-Church in Devonshire. It con- 
tained a detail respecting the analysis of the native salt, and a 
description of some peculiarities of the stone, (a variety of grey- 
wacke,) in the decomposing cavities of which the salt is now 
forming. . . 
A Machine was exhibited by the Reverend Mr Cecil of Mag- 
