144 Description of a Self-acting Ventilator, $c. 



escape of the heated air, and the other near the floor of the 

 house for the admission of cold air, will open and close again 

 several times in the course of the day, particularly when the 

 weather is showery, with intervals of bright sun. 



Believe me, 

 dear Sir, 



yours truly, 



John Williams. 



Pitmaston, 2d April, 1824. 



P, S. I beg to observe, that since I transmitted the above, 

 I have seen Mr. Mugliston's Paper,* on the same subject, 

 and it is rather remarkable that we should both have adopted 

 the same principle, without communicating with each other ; 

 For I had neither seen or heard of his self-ventilating ma^ 

 chine till long after I had transmitted this Paper. 



* Horticultural Transactions, Vol. v. page 502. 



