84 



MR. B. R. WATSON ON 



Table 0. 



Date. 



Number of hours' 

 sunshine recor- 

 ded.* 



Value of day in 

 arbitrary units. 



Date. 



Number of hours' 

 sunshine recor- 

 ded.* 



Value of day in 

 arbitrary units. 



Nov. 25 



8-1 



I'OO 



Jan. 2 



8-o 



0-99 



26 



8-i 



1 -oo 



3 



7"5 



0*96 



27 



8-o 



099 



4 



7-8 



0-97 



29 



8-i 



i-oo 



5 



7-1 



0-94 



30 



8-o 



0-99 



6 



8-o 



0-99 



Dec. 1 



7*4 



o'95 



7 



7'9 



0-99 



2 



8-o 



o-gg 



11 



7'3 



o*95 



3 



79 



0-99 



12 



7'9 



o*99 



4 



7*9 



0-99 



13 



5'5 



0-84 



5 



7'6 



096 



14 



79 



0-99 



6 



3*3 



070 



15 



7'9 



0-99 



7 



7"4 



0*95 



16 



8-o 



0-99 



8 



7-6 



0-96 



17 



7"5 



0*96 



30 



2-3 



0-64 



18 



8-o 



0-99 



31 



8-o 



0-99 



19 



8-o 



0-99 



Jan. 1 



8-1 



1*00 



20 



8-o 



0-99 



* Supplied by courtesy of C. W. Peake, Esq., Meteorological Reporter to Govt, of Bengal. 



This table was used to correct the determinations above mentioned, and thus was 

 obtained the number of days of bright sunshine required 1) to produce first sign of 

 fading ; (2) to reduce the shade to one-quarter of the original intensity ; (3) to com- 

 pletely bleach the fabric. These figures are given in Table I, opposite. 



The rough estimate of the relative values of the different days was quite sufficient 

 for the purpose, as an error of one day or more is quite possible in estimating both 

 (2) and (3). 



The amount to which the shades had faded at any time was determined by exami- 

 ning the strips (part faded, part unfaded) by the aid of a set of standards. These 

 standards were made by dyeing with exactly weighed quantities of pure synthetic 

 dyes (those dyes being chosen which are readily taken up by the fabric) : e.g., dye- 

 ings were made with Congo-red of 2-0%, ro%, 0-5%, 0*25%, 0-12%, 0-06%. The 



