Sir E. Home on the production and formation of Pearls. 275 



months show this wind to be the most prevalent. As it is from 

 this quarter that the greatest quantity of rain accompanies the 

 currents of the atmosphere, this circumstance appears to be an 

 additional proof (if any were wanted,) that the greatest quan- 

 tity of moisture is conveyed by this wind. In 1823, we had 

 198 rainy days; in 1824, 187; and in 1825, 169; but, in 

 1826, we have had only 147 days in which rain has fallen ; 

 and had it not been for the remarkably wet month of Febru- 

 ary, the number would have been much smaller. 



We have had very little snow, and that with the wind at E. 

 and S. E. The rain has fallen, excepting in two instances, in 

 very small quantities at a time. 



Art. XXIII. — On the production and formation of .Pearls.* 

 By Sir Everard Home, Bart. V. P. R. S. With observa- 

 tions by the Editor on the peculiar lustre of Pearls. 



In examining the organs of generation of the large fresh wa- 

 ter muscle, I very frequently met with what are called seed- 

 pearls, and these were always found in the ovarium, or con- 

 nected with the shell in which the ovarium lay. I at the same 

 time accidentally discovered that all oriental pearls that are 

 split into two halves have a brilliant cell in the centre. This, 

 however, where the pearl has been bored is destroyed, and 

 * Abridged from the Phil Trans. 1826, part iii. page 338. 



