^396 



Mr. C. H. Gimin^ham on a new [Dec. 7, 



and active amoeboid movements. C, C are connective-tissue corpuscles, of 

 which one is of such remarkable form and appearance that the least change in 

 it could be very readily observed. It contains a conspicuous vacuole, and it 

 sends its processes along the fibrils of elastic tissue, as formerly described. N 

 is a small nerve-trunk. M, striated muscular fibres. L, L are leucocytes — 

 migratory colourless blood-corpuscles. 



This specimen was kept under observation for eight days, during the whole of 

 which emigration continued. It remained absolutely unchanged, with the 

 exception that the vacuole of the corpuscle above described varied somewhat 

 in size. Thus on the fifth day it became somewhat more distinct than it had 

 been before. About the same time highly refractive granules and bodies 

 resembling Bacteria appeared, and the leucocytes present seemed also to contain 

 granules. On the seventh day it was observed that the circulation was growing 

 feeble, and the tissues were losing their transparency, a change in which the 

 fixed corpuscles obviously participated. On the morning of the eighth day it 

 was found that circulation had ceased. 



December 7, 1876. 



Dr. J. DALTON HOOKER, C.B., President, in the Chair. 



The Presents received were laid on the table, and thanks ordered for 

 them. 



The following Papers were read : — 



I. " On a new Form of the ^ SprengeP Air-pnmp and Vacnnm- 

 tap.^^ By Charles H. Gimingham. Communicated by 

 William Crookes, F.R.S. &c. Received August 30, 1876. 



[Plate 9.] 



Having had the honour of being with Mr. Crookes during the whole of 

 his recent researches on Radiation, and knowing the importance of 

 obtaining the highest degree of rarefaction possible, I have latterly devoted 

 much attention to the improvement of the " Sprengel " mercury-pump. 

 Having now succeeded in constructing an instrument yielding very 

 satisfactory results both in degree of exhaustion and rapidity of working, 

 I purpose giving a detailed description of it, together with a new 

 form of vacuum-tap which has been found exceedingly useful while 

 working with vacua. 



The instrument, owing to the number of accessories, at first sight 

 appears complicated. I will therefore first explain the principle of the 

 pump, tracing the mercury and exhaustion through the different tubes, 

 and then describe each adjunct separately. 



Assuming the pump to be empty, the reservoir A (fig. 1) is lowered 

 till its support rests on the stop (S) at the bottom of the stand (as shown 

 by dotted lines in the figure), the position of the latter being so arranged 



