The construction of timber, and the disposition of its component parts, as seen by the microscope, is the subject of the next chapter; a subject confessedly obscure. With what degree of success this attempt has been prosecuted, must be left to the judgment of the reader. The best treatise on this part of vegetation is that of M. Du Hamel du Monceau sur la Physique des Arbres. If either my time or situation in life would have permitted it, I should have followed his plan; but being confined to business and to London, I can only recommend it to those lovers of the works of the Almighty, who live in the country, to pursue this important branch of natural history. There is no doubt but that new views of the operations in nature, and of the wisdom with which all things are contrived, would amply repay the labour of investigation. Every part of the vegetable kingdom is rich in microscopic beauties, from the stateliest tree of the forest, from the cedar of Lebanon, to the lowliest moss and the hyssop that springeth out of the wall; all conspiring to say how much is hid from the natural sight of man, how little can be known till it receives assistance, and is benefited by adventitious aid. From the wonderful organization of animals, and the curious texture of vegetables, we proceed to the mineral kingdom, and take a cursory view of the configuration of salts and saline substances, exhibiting a few specimens of the beautiful order in which they arrange themselves under the eye, after having been separated by dissolution; every species working as it were upon a different plan, and producing cubes, pyramids, hexagons, or some other figure peculiar to itself, with a constant regularity amidst boundless variety. Though all nature teems with objects for the microscopic observer, yet such is the indolence of the human mind, or such its inattention to what is obvious, that among the purchasers of microscopes many have complained that they knew not what subjects to apply to their instrument, or where to find objects for examination. To obviate this complaint, a catalogue is here given, which is interspersed with the description of a few insects, and other objects, which could not be conveniently introduced in the foregoing chapters. By this catalogue it is hoped that the use of the microscope will be extended, and the path of observation facilitated. To avoid the formal parade of quotation, and the fastidious charge of plagiarism, I have subjoined to this preface a list of the authors which have been consulted. As my extracts were made at very distant periods, it would have been impossible for me to recollect to whom I was indebted for every new fact or ingenious observation.