6o6 
INDEX. 
359. fly to an amazing distance, 360. historical account -of 
silk, 360, 361. introduction of the broad-silk manufacture into 
England, 362. 
Silver (native), occurs in a variety of forms, iii. 492. seldom 
found pure — productive mines in England, 493. mineralized 
silver, 494. gangue, what, 495. silver mines, general account 
of — its properties, 495 — 499. 
Slickensides Mineral. See Minerals. 
Snail, excluded from the egg completely formed with a shell upon 
its back — first shell the basis of a second, and how that is in- 
creased, ii. 587. varied colours, how produced, 589. descrip- 
tion of the snail, 590. courtship, how conducted, 59] . remain 
torpid in winter — are exceedingly tenacious of life, 59 3. re- 
markable instance, 593, 594. experiments of Spallanzani re- 
specting the reproductive power of snails — Helix pomatia, a 
snail much esteemed by the Romans, 594 — 596. introduced in- 
to England — still admired on the continent, 597. 
Snake, ringed, perfectly harmless — where found, ii. 108. occa- 
sionally domesticated, 109. remains in a torpid state during the 
winter — Black snake of America, its agility exemplified, 110. 
of great use in clearing the houses of rats. 111. battle between 
swo snakes described, 112 — 114, 
Solen, its shape, ii. 555. manners and mode of taking it— de- 
scription, 556. 
Sphinx, Death’s head, an object of superstition, ii. 363. described 
— where found, 364. a type of the resurrection — lines by Dr. 
Shaw, 365. 
Spider, natural antipathy excited by the, ii. 514. its different parts 
described, 514 — 516. web of the house-spider described, 517* 
a very curious piece of mechanism, 518. damages in the net 
readily repaired, 51 9. faculty of counterfeiting death, 520. 
Peculiar labours of the garden-spider described — can exist for a 
great length of time without food, 520—522. Gossamer spider, 
interesting account of — water-spider, its habits described, 523 
— 526. Bird-catching spider, account of, 527. 
Squirrel, its great agility, i. 29O. change colour in high latitudes — 
migrate in search of provisions — their extraordinary manner of 
