th passengers; a Pullman car
weighs about 30 tons. Our steamers consume 5 lbs. of coal per
horse-power in one hour. And last, not least, one of the greatest
improvements we have had in steam propulsion is the screw. Again, I may
also name the great advantage derived from steam by our farmers in
thrashing out grain. The engines principally used in farm-work are what
are termed high-pressure, or of the same class as the locomotive. The
great saving in cost in the first place, the simplicity and ease of
action in the second, and the small quantity of water required to keep
them in action, are all reasons why they should be preferred. The danger
in the one, that is, the high-pressure, over the condenser, is very
small, and all that is required is common care to guard against
accidents. Steam being a steady power, is much to be preferred to
water, as by its constant and uniform action the tear and wear of
machinery is much diminished, and of course proportionate saving made in
keeping up the mill or any other machinery.

Having now, to the best of my power, so far as a single lecture will
permit, brought the steam-engine from 120 B.C. to the present time, it
only remains for me to say, that it shows how actively the mind of man
has been permitted to work to bring it to perfection by the direction of
an all-wise Providence, "who knows our necessities before we ask, and
our ignorance in asking." A traveller by rail sees but little of the
vast and difficult character of the works over which he is carried with
such ease and comfort. Time is his great object. No age of the world has
conquered such difficulties as our engineers have had to deal with, and
the result is now before the eye of every thinking traveller. Our
engineers were at first self-taught, and many a self-taught man has had
reason to rejoice in the time he spent in his education. Of these men we
have examples in Brindley, who was at first a labourer and afterwards a
millwright; Telford was a stone-mason; Rennie a farmer's son apprenticed
to a millwright; and George Stephenson was a brakesman at a colliery.
Perseverance with genius, and a determination to overcome, made them the
great men they were. That you may so persevere and strive is the earnest
wish of him who has this evening had the great pleasure of giving you
this lecture, and who feels so greatly obliged to you for the very
patient hearing you have given him.

_ON ATTRACTION_.[B]

_Gravitation_