326 PROCEEDINGS OF PROVINCIAL SOCIETIES. 



but in degree ;'" and that " the object which the philosopher aims at 

 in his researches is precisely the same with that which every man of 

 plain understanding, however uneducated, has in view when he re- 

 marks the events which fall under his observation, in order to obtain 

 rules for the future regulation of his conduct." It is true that it is 

 not every observer, however accurate, who can thread the maze of 

 consequences which are often perceived at a glance, by the gifted 

 mind, to result from a single fact, like Clairant, from some perturba- 

 tions in the motions of certain of the planetary orbs, conjecturing the 

 existence of a seventh planet, and the period of its orbit, many years 

 before it was discovered ; but the great provinces of observation and 

 experience offer some rewards to all who to common diligence unite a 

 desire to taste of the fruits of knowledge. 



Again, some of the noblest conquests of science have been nothing 

 more than applications and adaptations of known natural principles, 

 or influences which astonish by their very simplicity, from facts pa- 

 tent to every observer. Thus, the same principle explains the descent 

 of bodies to the earth's surface, the ascent of vapour, and even the 

 motions of the planets. The oscillations of a lamp in the cathedral 

 of Pisa, a phenomenon seen by numberless spectators before, sug- 

 gested to Galileo the isochronism of the pendulum, and led to the ob- 

 servation that a long pendulum vibrates more slowly than a shorter 

 one, according to the square root of its length. These simple facts 

 suggested the application of this curious instrument as the most cor- 

 rect measure of time, and an unvarying standard of linear measure ; 

 and in the hands of Newton it became the means of measuring the 

 intensity of gravity at different parts of the earth's surface, and 

 thence of determining its true figure, as Fontenelle observes, without 

 quitting his elbow chair. The discovery of the Torricellean vacuum 

 soon led to the application of the barometer as a means of obtaining 

 the most accurate admeasurement of mountain elevations. The same 

 object is attained by formulae founded on the difference between the 

 standard and the actual mean temperature, as indicated by deep wells 

 and shaded springs, or the depth of any place below the boundary of 

 perpetual congelation. A problem relative to a game of chance, pro- 

 posed by a man of the world to an obscure Jansenist, gave birth to 

 the doctrine of chances, or rather of probabilities, now a branch of 

 mathematics applied to almost every subject of human investigation. 

 Some of the most curious discoveries respecting the polarization of 

 light resulted from an observation made by the celebrated Erench 

 philosopher, Mains, in 1810, while looking through a prism of calca- 

 reous spar at the light of the setting sun reflected from the windows of 

 the palace of the Luxembourg. Hauy was led to his theory of the 

 structure of chrvstals bv the accidental circumstance that, while look- 

 ing over the cabinet of i\Ious. Defrance, a hexahedral prism of carbo- 

 nate of lime separated from a group, which, having a corner broken 

 off from the base by which it had been attached, led him to attempt 

 to detach similar comers from the other angles, and enabled him. 



