No. XXlJ APPENDIX; 295 



pound bodies in theii- elements, and convert two Isodies into a third, we 

 then obtain one idea of chemical affinity. 



It is not my province to show how we obtain the ideas of aU the 

 physical forces, or the relations of one to another : that will be the duty of 

 your different teachers. This part of the subject is confessedly difficult, 

 and wiU require your fullest attention and reflection. As youthful persons, 

 however, you can have but a faint glimmer of those great and glorious 

 principles which hereafter you will more fully perceive. 



This high mental faculty is termed the Wobmic pactjltt, which is 

 almost entirely absent in early childhood, then increases to manhood, and 

 declines again with advancing years. For the exercise of it, you must well 

 employ your time whilst young in the collection of observations for 

 reflection. Without facts you can have no thought, without thought yoa 

 can have no principles ; and it is upon the correctness of your principles 

 that your success in after-life will most materially depend. 



We have remarkable instances of the power of a knowledge of princi- 

 ples over the mind of those who are ignorant. Sir Harry Smith, when he 

 conquered the Africans, desired to show them his superior power. He 

 ordered a baggage-waggon to be placed at a distance, to which he had con- 

 nected wires communicating with a battery. When the Africans had 

 assembled, he told them at his command the waggon would blow up. They 

 marvelled. He spoke the word; they saw nothing. The circuit was 

 secretly completed, and the waggon was shivered to atoms. Some 

 voyagers, taking advantage of an eclipse, the occun-ence of which was 

 predicted by calculation, have stated that they so frightened the Indians, 

 that they obtained from them whatever was desired; and though 

 I entirely and utterly disapprove of this mode of proceeding, it never- 

 theless equally illustrates the power which is conferred by an intimate 

 knowledge of the great principles of science. 



By thought and reflection we are likewise enabled to form right 

 judgments in general ; and when two assertions, apparently different, are 

 brought before our minds, we can select that which is the true one. Last 

 year the merchants of London were startled by the large amount of gold 

 stated to exist in certain English rocks. Some of my friends were inter- 

 ested in a particular mine, which by the mechanical process yielded large 

 quantities of gold; but by chemical processes, only such an amount of 

 the metal was found as was insufficient to cover the expenses of extraction. 

 After much careful thought, therefore, we judged it most prudent to trust 

 to the chemical processes, but many persons trusted to the mechanical pro- 

 cesses and lost thereby various sums of money ; and in one case I heard 

 that a single individual lost as much as £4000 by this error of judgment. 



With all our care we shall not always judge rightly, or, judging 

 rightly, we shall come to wrong conclusions, because we shall sometimes 

 act upon wrong facts. We should therefore have much compassion upon 

 those who are proved to have formed erroneous judgments ; although true 

 facts and principles will always in the long run prevent mankind from 

 believing the plausible statements of quacks, pretendei's, and schemers. 

 We cannot judge rightly by our own unaided reason, for without a proper 

 set of facts and principles no judgment can be made; and we only 

 deceive ourselves if we call our thought a judgment without proper data. 

 Nevertheless, the tendency of man to judge with insufficient data is so 



