SCIENTIFIC SUMMAEY. 119 
the beach with splinters of timber^ and expending their force on Mr. Scott 
Kussell’s target behind. 
Gun Cotton. — Dnriag the meeting of the Eoyal Agricultural Society at 
Newcastle, Messrs. Prentice, who have introduced the manufacture of gun 
cotton in this country, exhibited its destructive powers by blowing up an 
enormously massive stockade. For this purpose they employed a shell 16 
inches long and 12 inches diameter, containing 25 lb. of gun cotton. The 
shell was fired by electricity, and reduced the stockade to utter rum. 
Drilling versus Flinching. — At the meeting of the mechanical engineers at 
Glasgow, a very lively discussion arose as to the relative merits of the drilling 
and punching processes of forming the rivet holes for the joints of wrought 
iron structures. The almost universally adopted process of punching is open 
to various objections ; it injures the metal of the plates between the rivet 
holes ; it makes a burred and conical hole ; the holes do not correspond with 
accuracy. On the other hand, the drill makes a clean accurate cut, but the 
process is tedious and expensive. Mr. Fletcher, however, described a machine 
on the general plan of construction adopted by Messrs. Cochrane for drilling 
the plates of the Charing Cross Bridge, and he stated that this machine 
drilled aU the holes in a large plate of one inch thickness in fifteen minutes, 
aU the holes being drilled at one operation. The drills are pressed with a 
force of 6 cwt. hydraulic pressure. 
Expansive Working of Steam. — Some extensive experiments on the ex- 
pansive working of steam have been made in America, under Government 
auspices, the main results of which we summarise below : — 
Steam condensed ; no steam jacket ; trials of 30 hours’ duration each ; 
engine performing the same amount of work in each triaL 
Cut oflF. 
Initial Pressure 
of Steam. 
Pounds of Water 
Evaporated. 
Pounds of Fuel 
Consumed. 
7-8ths 
30-6 lb. 
16,6221b. 
1,635 1b. 
2-3rds 
33-3 „ 
14,981 „ 
1,401 „ 
l-2nd 
... 38*1 ,, 
14,568 „ 
1,374 „ 
l-4th 
53-9 „ 
12,826 „ 
1,245 „ 
It will be seen that the economy of fuel working at l-4th cut off, over 
7-8ths cut off, amounts to about 25 per cent. 
Second series similar to first, but cylinder fitted with steam jacket ; — , 
Cut off. 
Initial Pressure of 
Steam in Boiler. 
Pounds of Water 
Evaporated. 
Pounds of Fuel 
Consumed. 
7-8ths 
25-93 lb. 
12,901 lb. 
1,212 
2-3rds 
25-41 „ 
11,267 „ 
1,069 
l-2nd 
34-64 „ 
11,188 „ 
1,086 
l-4th 
47-51 „ 
9,632 „ 
959^ 
MEDICAL SCIENCE. 
Fungi as Agents in the production of Disease. — In one of the numbers of our 
last volume . we detailed the curious experiments of Davaine and others, 
tending to prove that bacteria and other plants of a similar character when 
injected into the blood of animals developed certain diseases which proved 
fatal in a very short space of time. We have now to record the opinions of 
