38o 



SCIENCE. 



A third class cf observatoiies are these intended for 

 instruction in astroncmy. The requirements, in this 

 direction are so different from those necessary to re- 

 search that it is impossible to combine the highest 

 efficiency in both directions with the use of the same in- 

 struments. The number of observatories especially de- 

 signed for pure instruction are very few in number. 

 The instruments necessary for the purpose are of the 

 simplest kind ; indeed, so far as mere training is con- 

 cerned, the engineer's level, transit, and theodolite can 

 be made to serve most of the purposes of the astronomical 

 student. What the latter really wants is that training of 

 the eye and the mind which will enable him to under- 

 stand the theories of instruments, the methods of elimi- 

 nating the errors to which they are subject, and the 

 mathematical principles involved in their application. 

 In this, as in nearly every department of professional 

 education, we may lay it down as a rule that the wants 

 of a liberal and of a professional education are, so far as 

 the foundation is concerned, identical. We are too prone 

 to lead the student into the minute details of a subject 

 without that previous training in first broad principles 

 which, though it may not immediately tell on his progress 

 as a student, will be felt throughout his life to whatever 

 field of work he may devote himself. Such a transit in- 

 strument as Hipparchus might have made, — a wooden 

 level mounted on an axis and supplied with slits to serve 

 the purpose of sights, — properly mounted in the meridian, 

 could well be made to take the place of the transit instru- 

 ment for purposes of instruction. Scarcely any higher 

 skill than that of a cabinet-maker would be required in 

 its construction. The object at which the student should 

 then aim would be, with the aid of this instiument, to 

 determine the error of his clock or watch within a few 

 seconds. If he is really acquainted with the principles 

 of the subject, and has his eyes properly trained, he will 

 have no difficulty in soon learning to do this.— {North 

 American Review). 



MICHIGAN FLORA. 



By Charles F. Wheeler and Erwin F. Smith, Hubbardston, 

 Michigan. 



The following interesting sketch forms the preface to a 

 catalogue of the Phsenogamous and vascular Cryptoga- 

 mous Plants of Michigan, Indigenous, Naturalized and 

 Adventive, which can be obtained of W. S. George & 

 Co., of Lansing, Michigan : 



The climate of the Upper Peninsula ol Michigan is 

 colder than that of the Lower Peninsula, the surface is 

 considerably broken, especially in the western part, and 

 the flora is in many respects decidedly northern, resem- 

 bling in part that of British America, and in other re- 

 spects like that of N. New England and Canada. Pines, 

 firs, cedar, larch, junipers, elms, poplars, black ash, bass- 

 wood, maples, and birches, are the principal trees. 

 Pinus strobus, the prevailing species southward, is here 

 largely supplanted by its more northern and less valuable 

 congener, P. resinosa, whose tall, slim trunks are, how- 

 ever, in good demand for driving piles. Under-shrubs, 

 like Rubus Nutkanus and Taxus baccata, var. Cana- 

 densis, are common, and indicate a tendency toward nor- 

 thern types that we find more strongly developed in the 

 herbaceous plants. Among the latter we note as found 

 rarely, or not at all, in the Lower Peninsula, but fre- 

 quently northward, and often having a high northern range, 

 such plants as Anemone parviflora, Viola Selkirkii, 

 J'otentilla frigida, Stellaria borealis, Sa.xifraga Aizoon, 

 S. tricuspidata, Pim;uicula vulgaris, Castiltea pallida, 

 Halenia deflexa, Physalis grandiflora, Tofieldia, pal- 

 uslris, Salix adcnophylla, Eriophortim alpinum, Aspid- 

 iutn fragrans, etc., etc. 



The influence of climate on vegetation may be summed 

 up in a few words, The climate of the L6wer Peninsula 



is not as, severe of as that of the Upper, nor so even, but 



is subject' to frequent, sudden, and extreme changes of 

 temperature — as great a variation during the winter sea- 

 son as 53° Fahr. in less than 24 hours having been re- 

 corded. Such rapid changes more or less affect vegeta- 

 tion, especially the tender branches of cultivatfd trees, 

 which are sometimes seriously injured. In one or two in- 

 stances alike effect on our forest trees has been noticed. 

 The annual range ot temperature is about 116 , and the 

 annual mean 46'. Of tain-fall, including what falls in 

 form of snow, we have, yearly, about thirty inches. Our 

 snow-fall is much less, for the same latitude, than that of 

 New York and New England. In the center of the 

 peninsula, we seldom have more than a few inches at a 

 time. 



The proximity of the Great Lakes exerts a marked influ- 

 ence in equalizing the temperature and the effects are 

 marked upon our flora. 



Trees like Liriodendron Tulipifera, Asimina triloba, 

 Cercis Canadensis, Gleditschia triacanthos, Cornus 

 Jlorida, Nyssa multiflora and Morus rubra, which be- 

 long to Ohio and Central Illinois, have crept northward, 

 favored by the mild influence of the lake winds, through 

 the central and western part of the Lower Peninsula, 

 often beyond the middle, and the same is true of smaller 

 and less noticeable plants. 



As might be expected from the uniform surface of the 

 peninsula, the flora is much alike throughout. Probably 

 three-fourths of our species are common to all sections, 

 though by no means equally distributed ; some being very 

 abundant in one district and rare in another at no great 

 distance. In most cases such change is due to soil rather 

 than to difference in elevation, temperature, or atmos- 

 pheric moisture. 



The Lower Peninsula is covered with a deep drift of 

 alternating sands, clays and gravels, and the flora of any 

 section depends chiefly on which of these happens to lie 

 uppermost. With reference to its flora, the Peninsula 

 may be roughly divided into two great divisions — the 

 hard-wood and the soft-wood lands ; one representing 

 the Appalachian flora, and the other, {he Canadian. 



The hardwood country lies south of latitude 43°, and 

 consists of very fertile sand, clay, or loam, mostly cleared 

 of the original forest, and largely cultivated. 



The sandy or stony drift of many river valleys in this 

 section supports a heavy growth of oak, frequently in- 

 terspersed with walnut and hickory, while the margins of 

 the streams, and the neighboring swamps, abound in 

 soft maples, swamp and chestnut oak, white and black 

 ash, elm, hackberry, sycamore, bu'ternut and similar 

 trees. Willows, dogwoods, viburnums, and buttonbush, 

 are common shrubs in the swamps ; and hazel, hawthorn, 

 wild cherry and plum, June berry, witch-hazel, etc., are 

 abundant on the dryer ground. 



On the uplands, and away from streams, clay, loam, 

 and a peculiar blackmuck soil, supersede the sands and 

 gravels of the valley. The prevailing timber here is 

 beech and maple and oak forest in about equal propor- 

 tions. Beech and maple (Acer saccharinum and var. 

 nigrum) generally grow together, forming magnificent 

 forests of great extent. The best wheat farms are usu- 

 ally found on uplands near streams, where the oak tim- 

 ber gradually shades into beech and maple. Plains of 

 fertile sand covered with a low, or scattering growth of 

 oak (oak openings) are frequent, and always very desira- 

 ble for farming purposes. Four species of oak are usu- 

 ally found on such plains — Q. alba, macrocarpa, coccinea 

 and tinctoria. 



Marshes densely covered with tamarack are common 

 in this part of the State, and nourish in their thick shade 

 such plants as Drosera rotundifolia, Sarracenia pur- 

 purea, Rhus venenata, Ribes rubrum, Chiogenes hispid- 

 ula, Salix Candida, Smilacina trifolia, Pogonia ophio- 

 qlossotdcs and Calopogon pulchellum. Arborvita;, red 

 cedar and black spruce are comparatively rare. 



