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��But there still remains to be found the actual mechanism of thunder-storms, concerning wbich various more or less theoretical opinions have been published. The matter will prob- ably remain in doubt until settled by the eame kind of investigation Ihal demonstrated the inward spiral path of cyclonic winds. Synoptic charts for a stormy afternoon, with hourly or even haif-hourly intervals, and sta- tions only ft mile or two apart, would probably settle the question beyond disjiute ; and the first local weather scrtice that succeeds in preparing a set of such charts will gain a prize worth working for.
LETTERS TO THE EDITOR.
��UTtlrr-t ituMi U In all coin rrqulrtd a> ptoo/ 0/ good /ailA. Tbe iucatideioenC llgbt on BtsameiB,
Thf itiKtarice died In No. ItM of Scienee, of early clectrru liiiliiing uf slenmboaU by the incandescent Bygicni. Ihoiigb earlier than iliat given by Professor Trowbridge, ii nut Ibe earliest.
1 crosaerl llie Atlantic in May. 18P2, In Ihe *leamer City of Hirbinond, uf the lijman tino, which was beautifully ligbled by the incandescent system. It is my iinpressluii Ibat the lamps were of an English make, the form of the cnrbiin Hlnmeat being iume- wliat different from that then used by Edison and other Amerienns. C. U. Ameb.
Ctt oppf ng«ta ne B.
It is not iTiiprobitble ibat the Inipleiueni figured In a recent article by Miss Babbitt (iv. 620. fig. 3) could bave been at'eil as a fuel-breaker, when fastened in a wooden and bide handle; btit a more evident use for such notched pebbles, namely, as net-weights, Is seen In an industry of the presunt day among the gill-net fisbers, both Indian and white, of the Great Lakes. Ket-weightB uf this character arc produced in large quantities at all points on the lakes whercglll-uetling ta in vogue, fonnhig fruguently a part of the ballast in the boltoniB of the 'Mackinaw' tisbing-boats, and lying eontplcuoiisty scattered over Ihe sand and beach In the iieigbborbood of fisblng-stations. A less primitive appliance for sinking the nets is coming into use: so that the notched discoidal pebbles, attached to the net with short pieces of twine, are now re- garded asold-fasbioned by the more thrifty flslierm en. The unnotcbed pebble net-weights, bound with bark, of the Hed-Lakers, are interesting as a still more primitive form; but more extended obserralinn In gill-net appliances would bave shown Miss Babbitt that the notched form U of far more ntual occurrence than she leads us to suppose, and that It pos'-esses tons of examples on the shores of the Great Lake!-.
I have found such Implemente assqclateil with the remains of recent Indians (cliert chlpphigs, broken pottery, etc.) In the sand-dunes at Evanslon. The modern net-weighls are dUtlnguishabla from those of the chert deposits In only one particular, ibat while the surfaces of the formnr are smooth, and their
��notches rough and angular, those of the latter show on their surfaces the effects of disintegration from long exposure on the sand to atmospheric aganctes. Iheir notches, too. having aiisunied Ibe same crumbling ch»raclor as the no, of the pebble. A large number of them (over twelve) which came to my notice at one place indicates (heir use as nel-weiKhts rather tbaii as 'chopping-slflines,' W. A. Phillips,
Ecanilon, Ul.
Tbe uae oi alipa in ecientiSc correepondcnoe. I have been interested in Mr. Mann's and other articles on Gllng scientific notes.
Any one wishing to file such notes will And that a very convenient method of doing so is by the use of the Sbaonon file, which may be found at any large stationery store. The punch for punching the holes through the paper Is the most etmvpnlent I have seen, as (he holes are always the same dUunce apart, and at the same distiince from the edge.
S. p, SnanPLBs.
��The decadence a
��soieuoe about Boston.
��In a late issue (So. 104), Science comments upon the decadence of science about Boston. Is 11 not an explanation of Iliis decadence that more and more In law years the mental atmosphere of Bosloo has be- come one of Inielleciual finish, rather than of intel- ledual earnestness? Of course, each of these trails has its excellences, as each may be I'Xnggerated ; but the latter of the two certainly Is far more favorable to the active growth of science In a community. Moreiiver, llie effect of an intelleclnal aimnsphere becomes most evident n'ben it has bujimi lu influence the lives of y.iur.p men grown up lii lis midst, and who take their cne in lite from it. Is not Ibis effect to be noticed in ihe present case? X. C.
Eocb'a 'comma bacUlna.' In the reproduction of the drawing of the 'commk bacillus,' made to illustrate my paper In Science for Feb. 6. some defeeiB are noikcuble, to which It seems necessary 10 call attenllon, ina>much as the design was to represent as accurately ns ixis-ibto the mor- phology of this mnch-ialkud-of micm-organism. The ends of some of the comnins in the figure seem to be cut oS square, whereas in ilie slide and in the drawing ihey are all rounded. Since writing the pa- per referred to, I have beeiL favored by Dr. Koch wltli a slide of the 'comma biLcillus,' in which the long spiral forma a>e fwr nioie nunn-niu* than tu the slide sent to the Anny medical niusinim, from which the drawing was made. Several of these spiral fllameuta are often seen In a single field, and many of them are lunger than that seen in the centre of Hg. 1.
" Stebndebg, suryeon U.S.A.
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��CarliiT<
��1 babits of the muskrat.
��Sly observations of these animals were conducted principally along the banks of the Alleghany River In The vicinity of Warreti, I'enn., where these enemies of fresh-water bivalves are very numerous.
1". The muskrat opens the shell by first severing the posterior adductor muscle. This can readily be accomplished, as the animal wldom immediately empiies the branchial chamber after capture, but re- mams with the valves slightly gaping, with the siphons open, until it receives quite severe handling, upon which the water in the branchial chamber Is vlolenllT ejected. The valves will also partially open if the
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