As yet, I have only spoken of philosophy; there is, however, another
branch of knowledge, viz. science, which also requires great
concentration of thought, and which ought to receive some degree of
attention, or you will appear, and, what would be still worse, feel,
very stupid and ignorant with respect to many of the practical details
of ordinary life. You are continually hearing of the powers of the
lever, the screw, the wedge, of the laws of motion, &c. &c., and they
are often brought forward as illustrations even on simply literary
subjects. An acquaintance with these matters is also necessary to enter
with any degree of interest into the wonderful exhibitions of mechanical
powers which are among the prominent objects of attention in the present
day. You cannot even make intelligent inquiries, and betray a graceful,
because unwilling ignorance, without some degree of general knowledge of
science.

Among the numerous elementary works which make the task of
self-instruction pleasant and easy, none can excel, if any have
equalled, the "Scientific Dialogues" of Joyce. In these six little
volumes, you will find a compendium of all preliminary knowledge; even
these, however, easy as they are, require to be carefully studied. The
comparison of the text with the plates, the testing for yourself the
truth of each experiment, (I do not mean that you should practically
test it, except in a few easy cases, for your mind has not a sufficient
taste for science to compensate for the trouble,) will furnish you with
very important lessons in the art of fixing your attention.

"Conversations on Natural Philosophy," in one volume, by a lady, is
nearly as simple and clear as the "Scientific Dialogues;" it will serve
usefully as a successor to them. It is a great assistance to the memory