(lr Each hygrometgl shall comprise ,' two mercurial ttriiiiorrr.t*r, ;f *;;;it u}a drv bulb"of similar construction' antl equal in di*-ensiorr, scale tJ ii"itiooi of icale' They shall be mounled :'
on a frame with a suitable ""*oi' "ontaining water' :,
(2) The w'et bulb shall be clcsely .covered with a single.layer of muslln i kept wet uy .ein, oia wick uttaJ.-i-io ii uoa atopp-G iqt-6 t"Ut'.water in the 'tr reservoir. rne *osiin "or.iirg uoo-tt "'rrict< stratt 'bi ,,iituute for the purpose, * ::
clean and free from size c'r grease
(3) No part of the wet bulb shall.u" *ll!i'.I i.ncne1l1:9-t-1t drv bulbs t or less than I inch from fhe surfaceof the waterin the reservoir and ttre water $ ij reservoir snaff tl'l;l;; ii, "i rhe-side of it away from the dry bulb' F:
*
(a) The bulb shall be spterical ancl of suitable dimensions and shall be n freely exposed on all sides to th;;i; tf tttt room' '*
(5) The bores of the stems shalt be such that the positions of-the-top of ll4 the mercury column shall be *r"Ur, ;i;ir;;;th;6it uJ " aittance of 2 feet' $ !
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.iii Rules 26-30 l Bibar Factories Rules, 1950 [le - -(6) -Each thermometer shall be graduated so that accurate readings may be taken between 50 and 120 degrces.
- _(7) Every degree froq 50 degrees qplg I20 degrees shall be ctearlymark9d b-v horizontal Iines on the steam, each fifth and tEnth degree shall bL marked by longer -marks than the intermediate degrees and the temperature marked opposite each tenth degree, i. e., 50, 60,70,rg0,90, 100, II0 and I20.
(tl The qarki-ngs- as above shall be accurate that il to say, at no temperature betvieen 50 an-d 120 degrees shall be indicatecl readings, 6; in error by more than two-tenths of a degree.
(9) A distinctive number shall be indelibly nnarked upon the thermometer.
1.0)-Jh9 accuracy-of each t_hermometer shall be certified by the National Physical Laboratory, New- lielhi, clr anf other Laboratory, Institution or com-petent authority {PProved by the Chief Inspector in writing ,ra ru.t certifi-cate shali aiways be kept attached to the Humidity RegistJr.
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