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The U. S. Signal Service

The U. S. Signal Service image
Parent Issue
Day
18
Month
October
Year
1872
Copyright
Public Domain
OCR Text

ïjje PicigangUfflS Every olie who reads tho daily papers hat Um the regular moraitig anaounoemont of " weather propabilities " fnrniihed by the Blgnal-Bervioe burean at Washington. Usually thcir prediotiona are very rolíaMe. ïlio followingisadescrip tion of tho simple nmchinery by whioh the data are furnished for thoir calculations: Thero are 02 ?ignal stations in the T 111tod States, the extreme outposts being Portland, MniTir ; Key "West, Florida: Galveston : Sun Diogo; Portland, Oregon ; and Duluth. Each station is furnished with h. barometer, thermometer, hygronietor, vane, rain-gaugo, anenoiuctcr, and a clock. TLi barometer ís tho Green's standard, nncl is always carelully oompared with tho sfandard in the oth'co before issue tbr U3e. It is placed in :i room of uniform toniprrnture, not hpnted or too much oxposod to the sun. When not in uso. tho cover is Vcpt elosed. Wlion an obscrvation is taken it is opcnod, and the barometer slipped back into the box. Tho thermometer is hung at the height Of th; eyo, in the open air, facing the north, ín such a maniier that it is ftlwaya ín the shade. It is placed so as to avoid tho light roflecting from surrounding object, and protecteii from rain, blow, and hrtil. Tbe bygrumetor is an instrument used in detcrrniming the degreo of nioisturo in the atmosphere. It is pluced in the same ■heitor as the thermometer, and ncar it. The anemometcr is an instrument used to moasure the velocify and force of the wind. It is oomposed of littlo Raucers traveling around a perpendicual ironbar, ech at'ter the other, likc a dog trying to catch his tail. Tho ancmometer i fixed in a vertical position upon a post of snflioient height to bring it on a lovel with tho cye of tho observer, and must bc in an ezposed position, so as to receive the full foro of tho wind. The wiwkwvne is worked on the eaine principlfe as are weatber-cock. It is, however, of scieutific construction, and, by ineans of a dial at the base, gives with great oxactness the direetion of the wind in any poiut of the compass. The rain-gause is placed with the top of the funnel-shaped collector a foot above the surfnce of the ground, iirnily fixed in a vertical position. It is exaniined daüv ; thu amount of water it contains carefully mettsurod with á graduated rul, emptierl oml agiüu fixed in place. The elock wliicl is a good oue, koeps yashington time. With tiloso instruments none of which are complicated, the humidity of the tnxosphere, forcu, vulocity, aujd tho direetion of tho wind, state of tho thermometer and all tho particulars about the woathor, including the inuhesof rain-fall, are ascertained in overy part of tho Unitud States. Observations are mado at tbe several iatioTis Utree times every 24 hours, moraing, evoning. and midnight. As the clocks are all set by Whashigton time in each of the f2 stations, all the observations are taken at tho samo instant. By 12 P. M. overything being ready at the telegraph office, a wiro on each cirenit is surrendercd by the tolegraph conipany for about teu minutes, and the reports come rattling in. In about 40 minutes ftoin tho ttrae they commence coming tficy are all received, when they are maik ed on a map of the United States. The state of the barometer, thermometer, direetion of the winds, etc, etc, over th; whole oountry are seen at a glanco, and upon this as a basis,, the "probabilities" for tho jicxt2-f hotrrsarficalculated. The reports are received, tlmnslatud, set up for tho map, maps lithographed and printed, and ready for dist'ibution, and tho whole report in cunrse of transmission over the country, within an hour.

Article

Subjects
Old News
Michigan Argus