Page:Science vol. 5.djvu/22

 SCIENCE.

��[VOL. v.. No. l(39M

��portion is bidhII. Since, now, the heat of t'ombna- tion of cellulose Is the. snnic ns that of starch, Ac- cording to von Recbtinbcrg's detennlDatiotis,' the dlffereiica In the nutritive value of the two must l>e measured by ibe heal of combustion of the mari>li- gas and hydrogen evolved.

The well-known eitpt'rimenti of Hcnneberg and Stohmann on the rrspiration of sheep showed no considerable cscrelion of eiiher liyilrogen or marsli- gaa. In one of them, for exanipte, Ibe animal ate per day 1,218 grains of hay, and excreted I.ij grama of marsh-gas. Not having at band the original ac- count of the experiment, we will assume that the hay cont^ned only twenty-flvc per cent of crude Rbre. of which oop-half was digested. This amounts to Kia granis per day. This quantity of cellulose, it oxidized to carbonic add and water, would yield GTti,- 704 cal.' From this wq have to deduct the amount of heat carried oS in l.H grama of marsh-gas, which, according to Pavre and Silbennann, amounts to ll>,.i9S cal. There remain 6ii",H(i) eal., represeniing the wortii of the 152 grams of cellnlosc to the animal. The same weight of starch, if completely oxidised, would yield 0BO,8"iR cal.: in other words, the cellu- lose ael free In the Iwidy of the animal nluety-six and a hair per cent of l!ie energy wlilcli the same weight of starch would have done.

Xaturally these calculations are not exact; but they serve to show, tlial, If the heat liberated during the fermeutation of the cellnlose Is of use to the ani- mal, the nutritive value of cellulose does not fall so much below that of other carbohydrates as some are inclined lo l>elieve. H. P. ABUSnr.

��TuiRTV years ago the territory of Kansas was Jiot occupied by the white man, and, if we except a few acres cultivated by the Delaware Indians, no portion of Iier soil had been liirncd up by the plough. Her entire area was included within the vast and almost unknown region of the 'treeless plains' aud the 'great American deserL' During llial brief inler- veniog period, more ttian a miltion people, cliiefly of the agricultural class, have taken possession of her domain, and have already brought tier to the very front rank of the states of the Union iu the extent aud value of her agricultural products. History affords no other instance of the permanent occupation of BO extensive an area, previously unoccupied by man, by so large au agricultural population, in so short a space of time. Ilere. certainly, if human agency could anywhere affect climate, would such an effect l«! produced. Here, assuredly, if settlement ever in- creases r«nf«ll, will such increase be most marked and most unmistakable. Tliai such i

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nitr or 1 grun of wnt«r 1 ' L«IDro brIOfi) ilia ] cy I'tof. F. U,:?M.)W.

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��kl rcqulrtil In ntac ibr tcmpBrn- < nculcmy ot kImch, Not. aS,

��tually taken place, I believe to be established beyond a doubt. It is a circnmstaocc peculiarly favorable to the determination of the point in question, ttial, although the general settlement of Kansas by cultiva- tors of the soil is of such recent date, reliable obset^ vatlotis upon the rainfall bad been made at the military posts upon the eastern borders for a sufficient period to make possible a satisfactory comparison between the rainfall before settlement and after settlement. The records at Fort Leavenworth cover the longest period, and enable us to compare the nineteen years dlately prece<iing the occupation of Kansas by white settlers with the nineteen years immediately follow- ing sueb occupation. During the lirst period tka average rainfall was 30.1NI inches; durlug the second period it was 3U.21 inches; giving an average increaw of 5.21 inches per annum, — an hicrease of nearly twenty per cent. The Fort Leavenworth records. cover so long a period of time I nearly forty years), that the Increased average of the second half of Ibe period cannot be attributed to a mere ' accidental variation.' In the issue of Science for April 18, 18S4. it is slated that " the supposed increase in the rainfall in the drj region beyond llie Mississippi is not lx>rne i remnis of the signal-service." But the records of the signal-service npiin which this statement was hosed include a period of only twelve years of obser- vation (from 18TI to 1882), which Is undoubtedly loo sliort a period for cither establishing or disproving the fact of a 'secular' variation.

But the fact of an increased Kansas rainfall does not rest entirely upon the Fort l^eaven worth obser- vations. There are other stntioiis in Kansas whose records cover a much longer period than that of the longest established regular station of the signal- service. There are the twenty years' records of tlM U. S. military post at Fort Riley, the twenty foue years' records of the State agricultural college at Manhattan, and the seventeen years' records of the State university at Lawrence. If these several periods of oliaervation be divided into two o<)ual part), iu each case it is found that the avert^e rainfall of the second half is notably greater than that of the flrat half. At Fort Klley the increase amounts to S.05 inches per annum, and at Manhattan too. 01 inches per annum, and at Lawrence to S.Oii Inches per annum. Expressed in per cent, the rainfall of these three sta- tions lias increased in the second half of each period of observation, at Fort Riley, thirteen per cent; at Manhatlan, twenty per cent: and at Lawrence, over nine per cent. If the increased rainfall could be shown by [be records of a single station only, or if the several stations with sufficiently long periods of observation exhibited discordant results Isome Indi- cating a decrease, while others indicate an increase), or if even a single station indicated a diminisheid rainfall, the fact of a general Increase would lack satisfactory demonstration. Butthe entire agreement of the four slallons whose records have been used in a discussion of this question seems to establish tie- yond doubt the fact of an Increased rainfall in the eastern halt n( Kansas.

There can Ih? no [casonable doubt tlinl the sem^ral

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