The contemplation of the works of God, as exhibited in the material world, forms one of the most suitable, gratifying, and useful employments of his rational creatures. These works present themselves to our notice under different aspects, and require the employment of various methods for their examination. The results of these investigations constitute the different branches of Natural Science.

The examination of the forms, magnitudes and motions of the heavenly bodies, is the peculiar business of the Astronomer. In the prosecution of his object, he employs measurement and calculation, for the purpose of discovering the laws by which the celestial phenomena are regulated.

The beings which constitute this terraqueous globe, are subject to various changes, in consequence of their mutual actions on one another. These the Experimental Philosopher professes to investigate. When the actions here referred to are accompanied with obvious motions, but do not produce a permanent change in the constitution of those bodies subject to their influence, they constitute those phenomena which the science of Natural Philosophy professes to examine and explain. The instruments of investigation employed in this department, like those of the astronomer, are measurement and calculation, aided by experiment. When the actions which take place among bodies, produce a permanent change in their constitution, unaccompanied with motions which admit of measurement, they are considered as belonging to the Science of Chemistry. Experiment is the only instrument of investigation which can be employed with safety in this department.