VOL. XXII.] PHILOSOPHICAL TRANSACTIONS. 563 



291 inches, lm a wire, on which the plate ep slips up and down, parallel to 

 the tube of the thermometer cd. k, any point, at which the spirit stands at 

 the time of observation; suppose at 38 on the spirit-thermometer; slide the 

 plate EF till the index g stand at 38 on the air-thermometer, and if the 

 liquor in it stand at 38 likewise, then is the pressure of the air the same 

 as at the time of graduation, viz. 29.5; but if it stand higher, as at 30, 

 at I, then is the pressure of the air greater : and the division on the sliding 

 plate against the liquor, shows the present height of the mercury to be 29 

 inches 7 tenths. 



I had one of these barometers with me i n my late southern voyage, and it 

 never failed to give early notice of all the bad weather we had ; so that I de- 

 pended on it, and provided accordingly ; and from my own experience I con- 

 clude, that a more useful contrivance has not for a long time been offered for 

 the benefit of navigation. 



Of a Polypus in the Vena Pulmonalis ; and of the Structure of that Vessel. 

 By IVilliam Cotvper, F. R. S. N° 270, p. 797. 



I send you an account and the form of a polypus, which I took out of a child 

 of about a year old. Its first observable disorders were a quick pulse, and a 

 difficulty of breathing. In about four days the gums were observed to be 

 swelled, for which they were cut, and all symptoms disappeared for five or six 

 hours ; after which, they returned. Notwithstanding bleeding, and the appli- 

 cation of other remedies, the difficulty of breathing increased, the pulse be- 

 came still lower and quicker, and in four days more the child died. 



The body was opened, and the viscera of the lower belly were found well 

 constituted. In the thorax, the thymus exceeded the natural size, even in 

 children. The fore part of the lungs appeared to be well disposed, but the 

 back parts were very hard, and much inflamed. On making an incision on the 

 diseased part, purulent matter followed the knife in such quantities, from divers 

 cells, that it filled the wounds as fast as made, and the pieces cut from it sunk 

 in water. But as we approach nearer to the parts unaffected, the pieces 

 became gradually more buoyant, till at length we came to the fore part, which 

 floated. The cavities of the right auricle and ventricle of the heart were filled 

 with a polypus, which was continued into the superior and inferior trunks of 

 the vena cava. Opening the vena pulmonalis at the basis of the heart, I 

 found it there completely filled with a polypus, or coagulation of blood, which 

 was continued into all its large branches in the lungs, and were easily drawn 

 out, and when displayed appeared as in fig. 2, pi. 14. 



4 c 2 



