TH RBMOMETER-STANDS. ] 



METEOROLOGY. 



1101 



Thermometer-Stands. In comparing the readings of 

 one thermometer with any other, it is requisite that each 

 instrument should be placed, as much as possible, in a 

 similar manner ; without tliis uniformity, no deductions 

 can be drawn with any claim to accuracy. In looking to 

 the situation of instruments used by persons who have 

 not been aware of the necessity of providing themselves 

 with a thermometer-stand, some will be found facing the 

 north, others the south, south-east, north-west, aud, in 

 short, every point of the compass. Again, some are 

 placed from one to five feet from the ground, others ten 

 to twenty feet ; some in the angle of a large building ; 

 others exposed to the snn's rays, either during the morn- 

 ing or the evening ; some touching a wall, others at a dis- 

 tance from one ; in short, the situations vary in as great a 

 degree as the temperature deduced from the observations 

 made by them. To obviate these sources of inaccuracy, 

 the late Mr. Lawson constructed his "Thermometer- 

 Stand," a sketch of which is given below (Fig. 70). 



Fig. 70. 



This stand consists of a frame, which has been found to 

 answer the intended purpose very well. It is composed 

 of irhite deal boards, and can be constructed by any 

 carpenter. It consists of an oblong trunk T, 12 inches 

 by 8 inches outside measure ; to the opposite side of 

 which are nailed boards 5 6, at the distance of three- 

 quarters of an inch, and projecting about six inches from 

 fie trunk towards the north. Outside of these are nailed 

 o her thin boards c c, full half an inch distant, and pro- 

 jecting about four inches beyond the last-mentioned 

 1. .anls, also towards the north. These sides or shades 

 being multiple, prevent the sun from heating the interior 

 of the stand, where the thermometers are placed. The 

 top, or pent-board, P, is made double ; and the boards 

 are plaood full three-quarters of an inch distant from 

 each othi.T, and come forward so as to overhang, by a full 

 inch, the Night Index Thermometer, placed immediately 

 beneath, for the purpose of preventing rain or dew from 

 falling perpendicularly upon the bulb of the thermo- 



meter. The legs, L L, of the stand, are merely the con- 

 tinuation of the sides of the trunk. The board or feet, 

 FF, are loaded or fixed to the ground, to sustain the 

 force of the wind. The interior, T, is blackened to pre- 

 vent strong reflections of light. 



Fig. 71 is a ground-plan of the machine, which will 

 prove sufficiently clear to any intelligent workman for 

 its construction. The sides (and wood-work generally) 

 are of half-inch white deal. The distance or space 

 between the sides of the trunk T and the board or inner 

 side, t s, is three-quarters of an inch ; and the distance 

 from that board to the outer side, o s, is full half an 

 inch. The narrow boards, s s, are to be nailed, with 

 studs intervening, to the middle board or side, i s, and 

 are for the purpose of preventing the sun from shining 

 between the trunk, and the sides o s and i s, when near 

 the meridian. The sides are fixed, one upon the other, 

 at the required distance (viz., three-quarters of an inch 

 and half an inch), by numerous wooden studs, about 

 three-quarters of an inch in diameter ; and the 

 nails or screws passed through the sides and studs, 

 fix the whole firmly together. The whole is to 

 be painted white, and no other colour, except 

 the face of the trunk T, which may be black, as 

 mentioned already. 



Fig. 71. 



OS 



This thermometer-stand can be placed in any 

 eligible spot that may suit the convenience of 

 its owner ; its four sides should face the cardinal 

 ]>"ints, commanding therefore a true north and 

 south aspect. It can be visited on every side, 

 nnd bo free from all surrounding objects. The 

 thermometers nsed can be read off with tho 

 greatest facility, and the whole will be at a 

 known distance from the ground. Those instru- 

 ments placed on the south face will have tho 

 meridian sun, and those on the north face will 

 be always in the shade, in consequence of tho 

 projecting wings. The arrangement can be em- 

 ployed by any meteorologist, wherever residing ; 

 it is of a determinate form, height, and size ; it is not 

 costly, but firm, and can be placed on any open spot 

 that may be thought eligible for its use. The instru- 

 ments may be read off with the greatest promptitude, so 

 as to prevent or reduce errors arising from the person of 

 the observer being too long in the vicinity of the ther- 

 mometers. By the general adoption of this stand, in 

 struments placed upon it will all be used or observed 

 under similar circumstances, and deductions from them 

 be more correctly drawn than where there is no other 

 used. It follows, that observations made by individuals 

 wherever residing, either in Europe, Asia, Africa, or 

 America, if drawn from instruments thus similarly 

 placed, can be compared one with the other, with far less 

 chance of error than has hitherto been the case. 



Mr. Glaisher, F.R.S., has likewise constructed a stand, 

 differing from the one just described, but which is also 

 an excellent contrivance. (See Fig. 72. ) 



Rutherford's Thermometer. The mercurial thermbme- 



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