SCIENTIFIC SUMMARY. 
95 
of sand ; two cubic inches of granite, four cubic inches of marble, or ten cubic 
inches of sandstone, may be cut away per minute. It will be obvious that 
flat or curved surfaces may be alike acted on by this process, the blast being 
in all cases directed at a right angle to the exposed surface. The blast pro- 
cess, besides executing ornaments in relief, or intaglio, may be applied for 
cutting grooves in quarries and tunnels, for dressing stone, for cutting stone 
in lathes, for cleaning scale from metals, for graining lithographic zinc, and 
for producing — by the aid of stencils or photographic gelatine-^pietures, 
any variety of design, and even the most delicate line engravings. 
MEDICAL SCIENCE. 
Effect of Exercise on Temperature , and on the Circulation of the Blood . — 
One of the best papers that we have for a long time seen on this important 
subject is that which was some time since read by Dr. Handheld Jones, 
F.R.S., before the Royal Society. It is really one of the first instances in 
which practical use has been made of the sphygmograph in determining the 
action of the heart in excessive exercise. There are numerous sphygmo- 
graphic records given in the paper which will well repay perusal. The 
principal conclusions at which the author arrives may be thus stated : — 
1. That the heart’s force is, in most cases, more or less weakened by great 
exertion. 2. That the arterial contractility is probably always lessened, 
even when the exertion is moderate. 3. That after exhaustion the heart 
recovers sooner than the artery. 4. That the heart's action, in about one- 
third of the cases of severe but brief exertion, is increased in force. 5. That 
the acceleration of the pulse probably depends chiefly on exhaustion of the 
vagi. 6. That acceleration of pulse-rate has per se no effect in increasing 
intravascular pressure. 7. That the temperature is usually elevated by 
exercise from ’36° to 1°*8 F., but in rare instances, or after prolonged toil, 
may be lowered l o, 08 to 2°T6 F. 8. That the paresis of cardiac and heat- 
regulating centres, coinciding with consumption of nerve-force in motor 
centres, shows, that, in some way, one centre is capable of drawing upon 
another at a time of exigency. 9. That the dynamic test is indispensable 
to ascertain the lasting power of the heart, the tone of the vessels, and the 
validity of the nerve-centres regulating the temperature ; in fact, to gauge 
the radical as distinguished from the acting forces. 10. That the capacity 
to endure fatigue well indicates, cceteris paribus , a like power to endure 
disease well. 
Dr. Carpenter on Dr. Ferrier* s Researches on the Brain. — At two of the 
Sunday afternoon lectures of the Sunday Lecture Society (November 1873) 
Dr. Carpenter gave discourses on the functions of the brain and what Dr. 
Ferrier has done towards a solution of this difficult subject. The best 
report of these lectures is unquestionably that given by the “ Times,” which 
is even too long for insertion in our columns. However, we may take a 
portion of it, more especially that part which relates to the inquiries made 
recently by Dr. Ferrier : — “ The cerebrum of a bird may be entirely removed, 
as was long ago shown by Flourens, without destroying its powers of receiv- 
