750 REPORT—1890. 
Temperature a=] 
be] 2. Rai 
8 I 3 axtr Teo ere tes ain- 
1880-89 Means Extremes oi Za fall 
EO Bf 
Mean | Min. | Max. | Range} Min. | Max. aI 
° ° ° ° ° ° % 0-10 Ins. 
Halifax ; . | 465 | 39°6 | 53-4 | 13:8 | 10:0 | 89-0 83 70 | 36°55 
Wakefield . 47-7 | 41:0 | 544 | 13:4 | 11:5 | 868 84 73 | 28:01 | 
Bradford . . | 48:0 | 42-4 | 53-7 | 11:3 | 12°0 | 84-4 As 72 | 30°15 
Leeds. » | 488. | 42°6. | 55:h.) 12:5. |. 12:0. |.87-0 81 6:7 | 25°53 
Hull . . .| 47-1 | 39°9 | 54:3 | 14:4 6:0 | 85:0 81 6:3 |. 27:07 
Mean . a AneOin| 41d. Wl basso) Se | 10:3. | 86-4 814 | 69 | 29-46 
In order to render more perspicuous the relation which the above values bear 
to the mean and to each other, the deviations per cent. from the mean were 
deduced (all the deviations in temperature being computed in percentages of the 
mean temperature), with the following result :-— 
Temperature a= 
. »” 
AS eas | 2a =8 ‘Rain 
21) | nee = | ost A mo A |, tvain- 
1880-89 Means | Extremes eee Ba fall 
—— ie a 5° 
Mean | Min. | Max. | Range} Min. | Max. | 
| = — 
5 % % % % % % | % % % 
Halifax . Fal —38 —2 +1 —1 +5 +2 +2 | +24 
Wakefield . : = =| +1 +1 +2 +1 +3 +6 | -— 5 
Bradford . cally behead +3 -1 —4 +4 —4 | -3 +4 ]/ + 2 
Leeds. 3 | +2 +3 | +2 —1 +4 +1, -1 —3 | —13 
Hull . : .| -l = 3 | 7 = +3 —9 —3 —1 -9 |— 8 
11. Photographs of the Invisible, in Solar Spectroscopy. 
By ©. Prazzt Suyru, LL.D. 
The photographs submitted on this occasion are two, each of them murally 
mounted and measuring 40 inches long by 20 high. They represent in reality 
only very small portions of the faint ultra-violet of the Solar Spectrum, but on a 
whole scale of 57 feet long from red to violet, and are located quite outside the 
spectral limits of visibility to the human eye, with the grating spectroscope con- 
cerned, whether under summer or winter sun. 
Yet the previous empty fields of ultra-violet view became filled with wondrous 
detail as soon as they were entrusted for record to actinism and the photographie 
film. This, too, in dull winter weather, with a lamentably low sun, on December 
12, 1889, or when the eye could see only less than nothing. 
Some degree of power in photography to record further into the spectrum than 
the human eye has long been well known; but in this instance there had been 
supposed proof obtained of a positive incapacity of the grating’s metal substance to 
reflect ultra-violet, or even violet, light. Yet here this accusation has been shown 
to be false the moment photography was applied, and powerful pictures have been 
procured thereby, as witness these enlargements by Mr. 8. H. Fry, at Kingston-on- 
Thames, from the author's original negatives on glass. 
The definition is not indeed yet what the author desires, but he expects soon to 
make it so, by aid of a contribution lately received from the Government Grant 
Committee of the Royal Society; so that then, having a sufficient supply of 
electricity already on the premises, he may be able to photograph a more crucially 
telling comparison between certain earthly elements and the Solar Spectrum lines 
