UxMhited at the Nottingham Meeting. 
Ill 
where the material enters, aud where, consequently, most strength is required 
for the first breaking, and decrease in size outwards, the last teeth being 
small and very numerous. The revolving disc malces from 800 to 1,000 
revolutions per minute, and can be set to grind coarse or fine as desired. 
One feature of importance in this machine is that the stuflf 
escapes as soon as the requisite fineness is reached, and is not 
operated upon again and again as in some disintegrators. The 
machine grinds ahnost all kinds of substances, ranging from 
quartz to rubber, rags, and cork, and it is claimed that it can 
even deal with plastic substances. 
The Judges were of opinion that the output from this 
machine would be large in proportion to the power employed, 
while the work in progress, viz. the reduction of green bones, 
was very well done. This determined them to recommend the 
machine for trial at the next Meeting of the Society. 
Messrs. J. & E. Hall, of Dartford Iron Works, Kent, ex- 
hibited a Eefrigerating Machine (Ax't. 3962), which is a new 
and interesting ex- 
ample illustrative 
of the growth of 
science in refrigera- 
ting machinery, and 
would have been 
entitled to a Silver 
Medal, whether on 
account of novelty 
or merit, but for 
the fact that it does 
not come within the 
class of agricultural 
machinery defined 
by the Council as 
eligible for such 
distinction. 
Hall's refrige- 
rator is based upon 
the system of com- 
pression and lique- 
faction, through 
cooling and evapo- 
ration, of an anhydrous gas having a low boiling-point. The 
designer has chosen for this purpose carbonic anhydride, on 
account of its high latent heat of vaporisation, inodorousness, 
freedom from chemical action on metals, or the leather used for 
making joints, and because it is a material cheaply and easily 
Fig. 15. — HalVs Refrigerating Machine. 
