

ON ELECTRICAL OBSERVATIONS AT KEW. 123 
TABLE XI. 
Mean electrical tension at each observation-hour in the three winters of 184.5, 
1846 and 1847, with the mean diurnal period of winter. 

Year.| Mid.|2 a.m.|4 a.m.|6 a.m.|8 a.m.|10 a.m.|Noon.|2 p.m.|4 p-m.|6 p.m./8 p-m./10 p.m.|Mean. 

—_—!)— 









div. | div. | div. | div. | div. div. div. div. | div. div. div. 
1845.| 20°1} 20°2| 19°8) 23:5] 90-9} 136°3 101: 8) 85:2 8. 2 105°6 |148- 6 166°3| 96°7 
1846.| 29:2) 26:5 | 24:2) 49°2| 77:0} 106°7 | 103°3] 95°4| 89-2 |128-1 |146°9| 119°4| 90-4 
1847.| 23°9| 22°7| 23°6| 76°9|111°4| 146°6 | 138-9|137°9 pee 154°8 |176°1 | 151°9 }119°1 


_|Mean. 245 23°2| 22°7| 46°5| 93°71] 130-0 115-8|106-0 101-5. 129-4 |157°3 | 145°5 |102°1 


TaBLe XII. 
Excess or defect of the mean electrical tension at each observation-hour as 
compared with the mean of each winter in the years 1845, 1846 and 1847, 
and the mean of the three winters. 





Year.|Mid.|2 a.m.'4 a.m.|6 a.m.|8 a.m.|10 a.m.{Noon. 2p.m.|4 p.m./6 p.m.|8 p.m.|10 p-m.|Mean.| 
diy. | diy. | div. | div. diy. div. div. | div. | div. | div. diy. div. div. 
—|}—-|—/}—-|/-|/+]/+]-|-—|]+]+4+] + 
1845.| 76°6| 76°5| 76°9| 73°2| 5°8)| 39°6 | 8:1.]11°5 |11:5 | 89 {51:9 | 69°6 | 96-7 













-}/-|/—|-/—| +) 4) 4 +) +] + 
1846.) 61:2) 63°9| 66°2| 41°2| 13°4] 16:3 |12°9 | 5:0 | 1:2 |37°7 |56°5 | 29-0 | 90-4 
—~|—|;—-|—-/-} +}4+]4+]/ +) 4] 4+) 4+ 
1847.) 95:2) 96°4| 95°5| 42°2) 7°7| 27:5 |19°8 | 18-8 | 11°6 | 35°7 |57:0 | 32-8 {119-1 








—}—-|—|—-/-| +]}4+]+4+]/-—]+]+4] + 
Mean.) 77°6| 78°9| 79-4} 55°6| 9:0] 27°9|13°7 | 3:9 | 0°6 |27°3 | 55-2 | 43:4 |102°1 
Most of the remarks offered under the head of “Diurnal period, Year,” will 
equally apply to the present tables. There is, however, one feature that is 
very striking, viz. the greater range as well as amount of tension during the 
winter months, and that independent of the low readings during the early 
morning hours. The double progression is even more decided than in either 
of the former cases. In tracing the diurnal march we find the minimum at 
4. A.M., a comparatively gentle rise takes place at 6 a.M., after which the 
tension rapidly mounts until 10 a.m., the forenoon maximum; it then gra- 
dually declines until 4 p.m., the afternoon minimum, and from this hour the 
rise is very rapid until 8 p.M., the epoch of theevening maximum. A fall of 
11°8 div. takes place between 8 and 10 p.m., and then the enormous fall 
occurs between 10 p.m. and midnight, which we noticed in the yearly curves. 
The elevation of the evening above the forenoon maximum equals 27-3 div., 
and the depression of the intermediate minimum is as great as 55°8 div. 
The recess of the nocturnal maxima and minima from each other is interest- 
ce. The above phenomena are very clearly apparent in the annexed curves 
fig. 4:). 
On Entoating these curves with those of the summer half-year (fig. 3), 
and comparing both with the curves having reference to the entire year 
on p. 119, the influence of the winter curves on those of the year is readily 
seen: the yearly curves present precisely the same general features as the 
winter curves. Taking this circumstance in connexion with the greater 
number of higher readings in winter than in summer, it may be inferred that 
the higher tensions materially influence the general results. The influence 

