ted to them, attentively noting differences,
making comparisons and recognizing their underlying idea. Many before
Galileo had seen a suspended weight swing before their eyes with a
measured beat, but he was the first to detect the value of the fact.
One of the vergers in the cathedral at Pisa, after replenishing with
oil a lamp which hung from the roof, left it swinging to and fro; and
Galileo, then a youth of only eighteen, noting it attentively,
conceived the idea of applying it to the measurement of time. Fifty
years of study and labor, however, elapsed before he completed the
invention of his Pendulum--the importance of which, in the
measurement of time and in astronomical calculations, can scarcely be
overrated. In like manner, Galileo, having casually heard that one
Lippershey, a Dutch spectacle-maker, had presented to Count Maurice
of Nassau an instrument by means of which distant objects appeared
nearer to the beholder, addressed himself to the cause of such a
phenomenon, which led to the invention of the telescope and proved
the beginning of the modern science of astronomy. Discoveries such as
these could never have been made by a negligent observer, or by a
mere passive listener.

While Captain (afterward Sir Samuel) Brown was occupied in studying
the construction of bridges, with the view of contriving one of a
cheap description to be thrown across the Tweed near which he lived,
he was walking in his garden one dewy autumn morning, when he saw a
tiny spider's net suspended across his path. The idea immediately
occurred to him, that a bridge of iron ropes or chains might be
constructed in like manner, and the result was the invention of his
suspension bridge. So James Watt, when consulted about the mode of
carrying water by pipes under the Clyde, along the unequal bed of the
river, turned his attention one day to the shell of a lobster
presented at table; and from that model he invented an iron tube,
which, when laid down, was found effectually to answer the purpose.
Sir Isambard Brunel took his first lessons in forming the Thames
Tunnel from the tiny shipworm: he saw how the little creature
perforated the wood with its well-armed head, first in one direction
and then in another, till the archway was complete, and then daubed
over the roof and sides with a kind of varnish; and by copying this
work exactly on a large scale, Brunel was at length enabled to
construct his shield and accomplish his great engineer