Page:Science vol. 5.djvu/132

 (Vor~ T., Mo. 1

��SIaxy eaaays and some books there are to tell us what should be done with our forests, or with tlieii- remains. This ninth volume of the reports of the census taken in 1880, now before us, tells us what these forests are. First and briefly as to their general distribu- tion in accordance with the eltmate and eon- flgumtion of the country. There is, in the most general tei-ms, a forest of the Atlantic, and another of the Pacific region, widely separated tiirough a long stretch of the continent, more approximate at their northern extremities, and essentially but loosely joined along the Mexican borders flom Tesaa to southern California by a Tery peculiar arboreal vegetation. And even where the Atlantic and Pacific woods are most widely severed, as in about latitude 40°, the western own to a near relationship with the eastern along the line where the Rocky Mountains flank the plains. Together, the two compose one large whole, — a temperate North- American sylva, the harmony of which is not greatly disturbed by the intrusion of Mexi- can types into its southern borders. A more seriously discordant element, however insig- nificant geographically, but figuring rather prominently in the catali^uc, comes as a con- sequence of the southward extension of the peninsula of Florida, upon which a good num- ber of tropical West-Indian trees have effected a lodgment. Like other immigrants, these denizens must be received upon the same foot- ing with those more truly to the manner born, although they sensibly impair the homt^eneity of the United States sylva.

Next as to the genera and species of which our forests are composed, amounting, it ap- pears, to a hundred and fifty-eight genera and four hundred and twelve species- A con- siderable number of these, however, are only arborescent at their best, never attaining the magnitude of timber-trees; and forty-eight oJ the genera, and nearly sixty species, occur only in semi-tropical Florida. The systematic account of the trees fills two hundred and twenty pages of the volume. It is wonderfully full, not to say exhaustive, in the biblif^raphy and synonymy, is comprehensive as to geo- graphical ranges, particular in its statement of the ctiaractcr of the wood (the specific gravity and the amount of ashes being specified under

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��each species), and also its economical nses. But descriptive matters and nil botanical details, beyond a mention of the height at- tained by the tree, are scrupulouslj- omitted, l-^vcn the nature and appearance of the bark. characteristic as it generally ia, and sometimes very imjiortant in its practical applications, ii nowhere mentioned, except in a single line in. a single case, that of the canoe birch. ~ the difference between the cherry birch and the yellow birch, so striking in the bark and so slight in every other respect, is not alluded to. This is evidently done on principle. was necessary to draw the line somewhere, and I'rofessor Sargent has drawn it very taught. We should grieve inconsolably over the ex- clusion, except for our exiJectation that the author means to make amends in another work, in which the tree will stand for more than its timber. Let us note, in passing, that in any future publication ' I'almaceae ' should give place to ' Palmae.' It was a good thought to supply a separate aad full index to the ' Cata- logue of forest-trees,' as this part of the vol- ume is modestly entitled. The addition of as much descriptive botanical matter as there is of bibliography would have made of it a com- pendious treatise.

We will not complain that practical matters predominate in a census report, Partii.. 'The woods of the United States,' fills two hundred and forty pages, moat of it tabular matter. ' Woods ' are here used in the sense of timbers ; and this portion of the vokime records with much completeness the result of an exhaustive determination of thespeciflc gravity, the amount of ash, the weight per cubic foot, the tensile strength, the behavior under compression, and the fuel value of the wood of all the species. This great piece of work was done by, or under the direction of, Mr. S. P. Sharpies. The wood specimens are preserved in two ftJU series, — one in the National museum at Wash- ington, one in that of the arboretum of Har- vard university ; and the surplus material, worked into 12,9C1 museum specimens, has been made into sixty sets, and distributed to nearly as many educational institutions.

Any one wishing to know the relative speciflc gravity of the wootl of our trees has only to consult the table beginning on p. 249. lie will learn that all those which are heavier than water are of sem'p- tropical species, or of the arid south-western interior region ; that the Floridian Condalia ferrea leads the list (spe- cific gravity, 1.3020) ; that Cercocarpm fohus, the mountain mahogany of Utah, etc.. comes up to 1.07;il ; that the lightest conifer-

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