382 Scientific Intelligence. 
of Vesuvius. The ascent and descent along the lavas take 
about five hours. We had very fortunately Salvador! for our 
guide, who told us all about the different eruptions, &c. &c. 
The crater is not ^it all the thing I expected, but a gulph of 
most immense size, and one can see to the very bottom of it. 
I can scarcely believe what we were told, that it is 4§ miles 
round the crater, and that its depth is 2000 feet ; but it is a 
most horrid, magnificent sight. Here and there a quantity of 
smoke is seen curling up the rocky sides ; but at present the 
mountain is very quiet. All around is a dark, black looking 
waste of lavas, extending to the sea ; and, near the foot, are the 
vineyards of the Lachryma Christi. In spite of the sad exam- 
ples of Herculaneum and Pompeii, villages are sprinkled here 
and there, at the very foot of the m^quhtain ; and our guide 
told us, that one of them, called Torre del Greco, had now 
been destroyed fourteen different times, and another seven. 
The day was very clear and beautiful, and the view very fine. 
The country round Naples, towards the hills, is so rich and 
productive, that it is called the Campagna Felice ; but still the 
people are poor and miserable. 
34. Effects of an Earthquake on the Vegetation of Wheat . — 
It is a remarkable circumstance, that, since the great earth- 
quake of 1687, no wheat will grow on the coast of Peru. In 
some places, indeed, a little is raised ; but it is very unproduc- 
tive. Rice, on the contrary, yields a great return. Before the 
earthquake, one grain of wheat yielded 200 grains. 
35. Maize Grain remarkably retentive of the power of Ger~ 
minating.’^lt is worthy of notice, that the maize which is found 
in the graves of the Peruvians, who lived before the arrival of 
Europeans in that country, is still so fresh, that, when planted, 
it grows well, and yields seed, 
36. Improved Sliding-Rule for gauging Cashs. — The object 
of this ingenious instrument or new Sliding-Rule, invented by 
Dr Thomas Y oung, is to determine, upon principles which are 
entirely new, and with the greatest possible simplicity and ex- 
pedition, the approximate contents of any cask whatever, sub- 
ject to any further corrections, which either theory or experience 
may dictate in particular cases. An account of this invention 
will be found in the Quarterly Journal, No. 32. p. 357. 
