Page:Popular Science Monthly Volume 29.djvu/449

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AUGUST, 1886.

By P. H. DUDLEY, C. E.

IN the forests which have contributed so much to the industries and wealth of the United States there are seventy species of trees which have been and are of great commercial importance, and three hundred and forty more species which have an economic value. But few countries have so great a variety.

A section from the trunk of a tree of nearly the entire list of the species, gathered from all parts of the United States, can now be seen in the great and valuable collection in the American Museum of Natural History of New York City, contributed by Mr. Morris K. Jesup. The difficulties attending such a great work, so as to show the appearance of the wood and size of the tree with its bark, can only be fully appreciated by those actually engaged in making the collection. The magnitude of the work is without precedent; and, while it has been possible to transport across the continent a section of a tree, it has not been possible to fully protect some of them from the attacks of fungi, and some species will have to be replaced, while others by seasoning have checked the ravages of their fungi, but they show discoloration of the wood. To many this is an objection, but, by showing what species easily decay, it enhances the economic value of the collection. So many of our primitive forests have been cut, that many species for general use are already consumed, and the importance of these specimens for study, in making selections for substitutes, can not be over-estimated.

An inspection of the different species shows the marked diversity in the structure and appearance of the woods, and one is quickly relieved of the general impression that they are all alike. Examined microscopically, the differences in structure are sufficient for identifi-