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��Among the wondekj'ul acbievenients of modern explorers should be placed on record the history of the successful expeditiou of Capt. Willard Gl&zier in search of the ulti- mate source of the Mississippi River, This daring esplorer. at the head of a lai^e and well-equipped party, penetrated the untrodden mlderncsa of ceutral Minnesota, and reached Lake Itasca, which has so long been regarded as the source of the groat river. Not content with this achievement, he plunged boldly into the forest, and succeeded, after great esertious, in forcing his way three miles farther south- ward, where he came to a second lake, also drained by the Mississippi, and forming, as lie states, its uttermost head. To this lake lie gives his own name, that the fame of his achievement may be perpetuated. It is ijer- haps unfortunate, that, as this whole region was sectionized by the genei-al land-offlce sev- eral years previously, lines having been run at every mile, a prior claim to this great discov- ery may arise. In any case, however, the names of Capt. Glazier and John Fhenix as explorers will go down to posterity side by side.

��LETTERS TO THE EDITOR.

��r/iupoiMlr. TAi

��■o/g<K

��Tben

��of aBTioolture.

��In your notice, April lU, of tlio appointment of Col Coleman to be comiaiiBioner of agrifnlture, yon com- mend the selection because of his " knowledge of praclical agriculture, and his experience of men and affairs," and indirectly condemn it because he does not have " any special or Intimate acigualntance with the science oi agricnlturej" your idea seeming to he that the agricultural itepartment should be organ- iied as a ' scientiGc bureau, with a tecbnlcai expert at its he«d.'

Col. Coleman has one additional qualification, in which he differs from all previous commlsiilonen: he is without a pet botiby. Hla course will be to elevate the work of the bureau from the advocacy of some single theory, to the development of what It best in a variety of theorien. and ilie adaptation of thai best to the pracUcsl work <if the agrlcultnritt. To carry out such a course, it is not necessary that the bead of the bureau should be a ' let'linli^al ex- pert;' indeed, it is better that lie should not be. Technical experts In one or two or three branches of scientific agrlcuiiure are, as a rule, Ihose gentle- men who have bee» in their bimnets, and seem to be incapable of such universal control as ought to be re- quired: and experts in all iiraliches cannot be found. It one have the ability to distinguish aud recommend

��what is Iwst, to discover and make use of the ability of BpeclallsLs, to restrain llio disposition in any on« department of his general work to override or belittle the rest, that one Is the person to have charge as the general head. Such a person la Cni. Coleman. Hla experience of men and affairs, and the general ap- preciation of his fitness in the conditions yon pointed out, by all classes of men, prove the wisdom of the selection.

When the bureau is lo be properly organized as a Bcientilic one, will be after the so-called agricultural colleges, founded at so enormous an expense by Ibe general government, shall have done what they were intended to do, — raise up young men and women, first, to an appreciation of what scientific agriculture Is capable; and, second, to au educational ability to pursue and apply It. Until the old ruts are aban- doned by men capable of understanding the trenefit of a new and well-made road, such men to be those who are praclical workers themselves, there will be no use of attempting science in a place the province of which is really only the collation, selection, and diffusion of such knowledge as can be used in the gradual development of all the resources of the coun- try. When the work of such an education is begun at the right end, it will have its natural sequence in a bigber gradation of the work of the head of the

Sricultural bureau, if any thing higher than that lich will be accomplished by the new commissioner is needed. Ana. F. Hartbt.

ei. LoDia, .\pril le.

Auroraa.

Various speculations are niPt with from lime to time as to the extent of any individual display of an aurora. A prominent French writer has recent- ly attempted to show that auroras are not widely extended, and has instanced the case of the most biilllanl aurora of modern limes at Bniasels, Belgi- um. This phenomenon occurred on Feb. 4, 18^; and the writer emphasizes the fact that It was not seen at Godthaab, Greenland. Meteorological obsra^ vations at the latter place for (his dale are not accet- sible; but there Is Utile doubt that, if there weresui^, it would be found that the sky was clouded, thus pr«- venting the appearance. At all events, the observar tions made on the American polar steamer Polaris, which wintered about four hundred miles north of Godthaab, show the must brilliant aurnra of the winter on Feb. 4, The same aiu-ora was seen throughout the northern United Stales.

When we consiiter, that, as shown by Professor Loomis, during a maximum period of sunspots Ifaere are also the greatest number of auroras, and that great solar outbursts are followed or accompanied by magnetic slomis aud brilliant auroral phenomena, we are led lo the view that the cause of the latter may be superlerrestrlal, acting either directly or Indi- rectly through Induced earth-currents.

It would seem as though all auroras are a mauifes- tation of cosmic energy, and that Iheir extent and brilliancy are limited by the amount of energy, bj Ihe vapor in the air, by the temperature, etc. Pn>. feasor I.emstrum in Finland obtained a simulation oC,

the aurora by artificial means during one winter; "_ ^

during the next winter, which whs barren of brilliant. aiu\)raB, both he and Professor Tromholl, the Isttarj in Iceland, failed in this. It may be Ibat the ~ success was owing as much to earth-currents, or KJ condensation of atmospheric electricity, i artificial means employed.

The question of the source of the electricity an aurora is an Impartanl one in meteorology

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