4-2 Description of an Instriimcrii io ascertain 



greater than the circulating fluids can be expected to con- 

 tain at any one time, as it goes offbv the secretions nearly 

 as fast as it is received into the l)lood- vessels. In a mo- 

 derately sized ass, more than two drachms musi.be dissolved 

 jn the blood before its presence there can be detected. 



That the fluid contained in the cells of the spleen is se- 

 creted there, is rendered highly probable, since it is most 

 abundant while the digestive organs are emploved, and 

 scarcely at all met with when the animal has been some time 

 without food. The great objection to this opinion is, there 

 being no excretory duct but the lymphatic vessels of the 

 spleen ; these, however, are both larger and ntore numerous 

 than in any other organ ; thev are found in the ass to form 

 one common trunk, which opens into a large gland on the 

 side of the thoracic duct, just above the rcceptaculum chyli ; 

 and when the quicksilver is made to pass through the 

 branches of this gland, there is a trunk equally large on the 

 opposite side, which makes an angle, and then terminates 

 in the thoracic duct. This fact 1 ascertained at the Vete- 

 rinary College, assisted by the deputy professor Mr. Sewell, 

 and Air. Clift. These lymphatic vessels are equally as large 

 as the excretory ducts of any other glands, and there- 

 fore sufficient to carry ofi' the secretion formed in the cells 

 of the spleen; and where a secretion is to be carried into 

 the thoracic duct, it would be a deviation from the general 

 plan of the aniinal oeconomy, were any but lymphatic ves- 

 sels employed for that purpose. 



It is a slronij circumstance in favour of the secretion be- 

 ing so conveved, that, in the last experiment, the lacteals 

 and cells of the spleen were unusually turgid, beuio' j^laced 

 under similar circumstances, the thoracic duct being so full 

 as not to receive their, contents. 



The purpiises that are answced by such a secretion frotn 

 the spleen into the thoracic duct cannot at presetit be ascer- 

 tained. 



VII r. Darripi inn of 071 Instrument to ascertain lite Velo- 

 cities of MacLiiiery. By Air. Bkyan Donkin*. 



.Sir, X BF.G leave, through vour means, to lay before the 

 Sorietv of Arts, &c. an mstrnmeiil of my invention, for 

 indicating the velocity of uiachmes, and which may not 



* From Transnrlin-^'! n*" the Snriflu Ar the Knr'oiror'nnpnt nf/frt^, Mnniific- 



ftirrs. anil Cri^uynerre, for iHlO. Tlic tiocicty voted their gold nied;il to 



Mr. B. Doiikin tor xliis invention. 



imnroperly 



