The Red Spider. 4 figures.

Japanese Peppermint.

VII. NATURAL HISTORY.--The Recent Eruption of Etna.

The Heloderma Horridum.--Illustration.

The Kangaroo.

VIII. ARCHITECTURE.--Design for a Villa.--Illustration.

IX. BIOGRAPHY.--William Spottiswoode.--Portrait.

X. MISCELLANEOUS.--Physics without Apparatus.--Illustration.

The Travels of the Sun.




FARCOT'S IMPROVED WOOLF COMPOUND ENGINE.


In a preceding article, we have described a ventilator which is in use
at the Decazeville coal mines, and which is capable of furnishing, per
second, 20 cubic meters of air whose pressure must be able to vary
between 30 and 80 millimeters.

In order to actuate such an apparatus, it was necessary to have a