D^ESCRiPTION OF A TACHOiVtETiEK. 1^1 



the mucus as above said, with some globules, and also »' 

 small' proportion of the self-coagulable lymph; which ap- 

 pears, on' agitating; murfis in a large proportion of cold 

 water, in the form of leafy and fibrous masses*. The same 

 stiCretdry orirans, it is easily conceivable, may, in a diseased 

 state, be excited to separate also selt-coagu sable matter 

 from the blood, with move globules, tn such a state as to 

 become pus. Hence, such a comnnix'tuie of the tWo sub- 

 stances must correspond to the opaque, viscid, expectorated 

 sputum, of which I am writing. 



If I thought farther reasoning proper, it would be mani- 

 fest, that all the phenomena, both in health and disease, be- 

 longing to the various kinds of sputum. Consist with the 

 theory above delivered. 



VI. 



Description of a Tachometer, or an Instrument to ascertain 

 the Velocities nf Machinery: by Mr. Bryan Donkin, of 

 Fort Place, Bermondseyf. 



JlN the employment of machinery it is evidently of great Advantageous 

 itpportance, to be jjvovided with an easy and ready method '"^^^I^'^'^'^ 

 for discovering at all times, whether the motion of the madunery. 

 machine is quicker or slower than what is known to be best 

 adapted for the object in view. This advantage, it is hoped, 

 may be derived from the tachometer; for it is an instru- 

 lueut which requires only to be adjusted once for all to any 

 p^tvpular machine, and then it will alv^ays be ready with- 

 out the help of calculation or of a time-piece, to indicate in- 

 stantly upon inspection the slightest excess or defect in the 

 actual velocity. 



A front view of the tachometer is represented in fi^. 1, An instrument 

 and a side view in fig. 2, of PI. HI. X Y Z, fig. 1, is the ^osgdes^^ibed. 

 vertical section of a wooden cup, made of box, which is 



* Scrum of blood appears always to contaia self- coagul able lymph, 

 vhich is deposited on standing ; and this appearance led G'aber, Priiiglej 

 and Culien, into the erroneous opinion of this deposit being pus itself. 



t Trans, of the Soc. of Arts,, vol. XXVIIl, p. 183. The gold medal^; 

 was. voted to Mr, Donkin fqr this inyention, 



drawn 



