
ae 
ON ELECTRICAL OBSERVATIONS AT KEW. 191 
minution of temperature in the present instance at Greenwich was 15° in 
26 minutes, but nothing further than the fall of a fine shower of rain 
occurred ; probably the path of the heavy rain did not cross the Greenwich 
Observatory, although the instruments there were influenced, 
(™) June 18, 1844,—This thunder-storm, which exhibited very interesting 
phzenomena at Kew, did not extend eastward so far as Greenwich; neither 
thunder, lightning, rain, nor any affections of the electrical instruments were 
observed there; the only record at all bearing on the subject is one that in- 
dicates the presence of cirro-stratus. During the whole time the sky was 
sompletely overcast at Greenwich. As illustrating the rapid succession of 
phenomena on these occasions, as well as some of the suggestions in the 
preceding note, it may not be uninteresting to subjoin the entire record of 
the observations at Kew. 
TaB_eE XCIV. 
Phzenomena of a Thunder-storm observed at Kew on June 18th, 1844. 













Time Pheenomena. Tension. Spark. Wind. 
hm ° in. 
3 40 p.m.*| Rain beginning .......sceesssseseeeness Henley 22 P. ..1...Jecs..ecnneee Ss. 
oi Cd ee Rede ecgean acted ceesnncesass Henley 40 P. ...... 0-300 S. 
BRM Ys “lerp ces sinpcacscctocsnesaverseecceebeswasess’ Henley 50 P. ...... 0400 S. 
3 55 p.m. | Distant thunder............-seseeeeee- Henlen/ PayPrinks sae tia S.S.E. 
4 Op.m. | Distant thunder...o. seers Henley 5 Ni, .cssssloscecesvoess 8.S.E. 
RNR RT ALAS DD) liisagnissaoniss $3 sandeep s¥snien of Henley 60 N. (a)...|...-00-000 S.S.E. 
4 4p.m. | Distant thunder; no rain............ Henley 65 P. (d)...| escesssseee s. 
4 8p.m. | Distant thunder; no rain............ Henlev 60 N. ......]...cceeseeee 8. 
4 10 p.m. | A few drops of rain ......ccee ee eeee ee Henley 59 N. ......Jeesseseeee 2 s. 
Beda pas) Al flash fie seits cede eesccedssessenevses Henley (ce). 
415 p.m. [A flash $ ....cc.ccceeeceeeeeesenseeeee ones Henley 60 N. (d). 
|4 21 p.m. | Distant thunder; a little rain ...... Charge gradually fallling. : 
4 24 p.m. [A flash ....c..cessceessceccaceeeneeses No effect on electro/meter. ...| $.S.W. 
4 27 p.m. | Rain increasing ...............eceeeeeee Volta 10 Po oo... face ssseeenes 8. 
4 34 p.m. | Heavy rain ....ee..cceececee renee neers Henley 35 P.(e)...| 0°300 S. 
4 35 p.m. | Heavy rain ...scccscseessesesenureesenees Henley 40 P. ......) 0°350 
| 4 47 p.m. | Sudden fall and gradual rise of elec|trometer. 
4 51 p.m, | Heavy rain.....ccccsecsessccscsreeneces Volta 7N....... aeancAnaa S.S.W. 
Bd) Op.m. | Heavy rBit.......ccscccsssucesscerencenee Henley 5 N. ......Jeccseesseeee 8.5. W. 
5 4p.m. | Heavy rain and distant thunder ...|Henley 20 N. (/). 
Prrbeperoy WING TAIN, Foats.s Jose scseces wnyeochivccs Herleyr D7 Ni) 5 < ssip] chive sn seh se S.E. 
5 30 pom. | No rain .......csececeseceennee speeay cnr Henley 15 N. ...0..|ecesesssnens S.E. 
5 37 p.m. |Norain ......... sole lee haber Segeeiaes Molta: SON. ss. catlgerseegeacce S.E. 
PRO Tere | NOGA... ve cseacassvenscinareesayeesess Woltagt Ober ccccralrcaseesaccad S.E, 
The following notes by the writer of this report may probably assist in 
more distinctly particularizing the principal features of the above-recorded 
phenomena. ‘The references are in letters of the italic alphabet. 
_ (a) The occurrence of the flash and the increase of the negative tension 
may indicate the approach of the cloud as well as the formation of rain. It 
would appear that from 3° 40™ to this time, 22 minutes, rain had been falling, 
but not such as to lead the observer to record it as heavy. 
(6) The maximum tension ; rain had ceased, but great oscillation of the 
charges existed. 
(e) This flash appeared to exert a momentary influence on the conductor; 
the tension was slightly declining, but increased after its occurrence. 
_ * At 3> 35™ p.m. distant thunder and lightning, Volta at 50° pos. 
heard at 3 p.m. 
+ Henley fell from 55° to 20°, and quickly rose again. 
t No effect on the electrometer, a 
Distant thunder was 
