186 
I. P. Косн. 
The variation of the co-efficient of refraction according 
to the time of day. 
x IX | У Skerry 
Date Hour | Temp. dk Jk 4k 4k 4k 
+++ | ++) ++) + + | + 
24. Aug. ... | 3215/+ 26 55 261 175 | 242 242 
98. NN 6240) ene 39 36 | 39 51 
14. Sept. .… | 5240 |-= 5.0 74 24 | 48 79 
16. June ... | 2200|+ 14| 23 84 | 108 238 
Mean . | 42.1 +48 | +101 | +53 + 85 + 152 
9. Aug 9200 + 3.5| 26 132 | 364 
12. Sept 9230 |-= 2.0) 62 39 10 72 
мо BRAG) ol 76| 24 37 
21. Oct..... | 8240| 20.4| 203 186 | | 
16. June 6210 + 1.6, 40 51 83 | 549 216 
18 9800 | + 2.4, 6| 59 | 16 | 
Mean 82.2 | 130,058 + 25 — 10 — 44 
23. July 10250! + 6.2 4| 11 115 122 
DE 9245 + 5.2 103 142 | 154 289 
ie 11200 |+ 5.8| 25 25| | | 12 
24. Aug 10240| 0.0] 19) 59 | 60 | 108 15 
al, == 11200 | -=- 0.3| 38! 55 | 35 | 24 58 
11. Sept 10200 | 3.4| 28 195| | 74| 89 
ln = 11210 |-+ 3.0| 97 175) | 79| 87 
10 Oct. 9240 | +- 14.6 27 т 28 
31. Мау 10210 | -= 2.8 206 180 | 79 342 
16. June 10230 |+ 1.7| 37 77| 40| 31 
Mean.. | 108.5 | +10 | +7 + 5 + 2 +114 
2. Aug. 1r30 + 6.5) 18 128! | 84 149 29 
u 2p00 + 8.8| 10 | 41| 94 | 181 
Е 1210 |+ 30| 57 И: | 97 392 
Oct A 0240 | + 10.2 42| 4 | 31| 13 
10. — 1250 | = 126| | 2| | 36| 14] 50 
21%. | 1050| 1b. 90!  |149| 9 
16. June... | 2r00|+ 2.5| 35| | 26] | 15] [19 
22. — 1220 | + 44 4| 64| | 52| |244 
Mean.. 12.5 +2 +7 | +14 | +45 +2 
24. July ... | 4240|+ 21| 24 69 171| |394 
23. Aug. ... | 2r30|+ 1.7111 163 23 | 45 
8. Sept. ... | 2P50 | 1.6] 66 39 || 36 | 55 30 
A= 2p50 | 2.2| 77 67| | 65 
= 3210 |= 21| 66. 76 | 38 | 66 
15, 2“ 3P20 + 6.9| 56. 95 | 35 | 69 
17. AI 9550 |= 38 |168 43 | 52 41 26 
15. June ... | 2P10|+ 2.8|111 101 |134 224 
9. July 2p30 | + 11.2 60 | 137 113 64| 2p50 = 
Mean.. | 3P.0 | о | aa 67 - 99 ae 
