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Mr. J. A. Ransome, F.R.C.S., offered some “Suggestions 
for the Improvement of the Air Pumps used in Physical and 
Chemical Researches.” 
Explanation of the diagram — 
Fig. 1. 
A A' BB'. Represent the cylinder, which is to be most 
accurately bored and polished. 
A A'. The top or cover (having a concave surface below), 
which is to be screwed to the upper flange of the cylinder 
and made perfectly airtight. 
aa. Small tubular apertures communicating between the 
cylinder and the globular chamber GG', placed round the 
tube TT', and capable of being closed above by the lower 
surface of the ring UV, forming a valve opening upwards. 
BB'. The lower flange of the cylinder, to be attached to 
the stand, and admitting of a bottom (not airtight) through 
which works the piston rod PR. 
CT. ‘The eduction tube for the passage of air withdrawn 
from the receiver on the pump-plate PP'; and also for the 
conveyance of air to the condensing receiver on the plate CP, 
when the machine is used as a condensing pump. 
CP. A second plate for a receiver in which air or gas 
may be condensed, either simultaneously with, or distinct 
from, the rarefaction on the plate PP'. Such a receiver 
would require to be secured by a cross-bar and screws, which 
are omitted in the sketch, as likely to complicate it. 
GG'. A globe of two hemispheres joined by flanges. 
Through this globe passes the tube TT' from the pump-plate 
PP' down to LV (the lower valve) ; at its lower end a cage, 
cc', open at the sides, supports a polished steel ball, which is 
accurately adjusted to the concave surface of the end of T'P', 
forming a valve opening downwards. 
Within GG' this tidje passes tightly through the cover of 
the cylinder, having a scries of small tubular passages around 
it, until it emerges from the flat bottom of the globe, which is 
