1855.} 



THE SOLAR ECLIPSE OF 1854. 



179 



Toronto Ohservatoi-y. Height above sea level 342 feet. 





TuEK. IN Shade. 



v=.^ ^-"-- 



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Wind. 



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a 

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 3 



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a 



.H 



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o 



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h. m. 

 3.30 



66!9 



61°1 



o 



6.8 



0.4.59 



.71 



86?4 



60?4 



29.632 



SWbS 





.35 



07.0 



61.1 



5.9 



.458 



.71 



86.2 



60.4 









.40 



06.7 



60.7 



6.0 



.4.54 



.71 



86.9 



60.0 



29.630 







.45 



06.9 



60.9 



6.0 



.454 



.71 



84.0 



59.8 









.50 



6.5.8 



59.9 



5.9 



.426 



.70 



82.7 



59.2 









.55 



66.1 



60.0 



0.1 



.437 



.70 



82.8 



59.0 



29.628 







4.00 



60.0 



00.0 



6.0 



.438 



.71 



82.6 



59.2 





SWbS 



2.9 



.05 



65.8 



59.6 



6.2 



.428 



.70 



82.5 



59.0 









.10 



65.7 



59.0 



6.1 



.429 



.70 



82.4 



58.2 



29.628 







.15 



6.5.6 



59.5 i 6.1 



.427 



.70 



80.1 



57.9 









.20 



6.5.0 



59.5 



6.1 



.427 



.70 



77.8 



57.8 









.25 



65.2 



58.5 



0.7 



.402 



.67 



77.6 



58.0 



29.620 







.30 



65.4 



58.3 



6.1 



.408 



.70 



75.0 



58.0 









.35 



65.0 



58.6 



6.4 



.408 



.68 



74.4 



67.8 









.40 



64.9 



57.6 



7.3 



.381 



.64 



72.6 



58.0 









.45 



64.9 



58.8 



6.1 



.416 



.70 



72.4 



58.0 









.50 



64.8 



58.3 



6.5 



.402 



.67 



69-4 



58.0 



29.624 







.55 



64.0 



58.1 



5.9 



.405 



.70 



67.2 



57.8 









5.00 



64.0 



57.9 



6.1 



.401 



.69 



6.5.1 



57.2 





SWbS 



2.7 



.05 



64.1 



57.7 



6.4 



.393 



.68 



63.4 



56.8 









.10 



64.0 



57.6 



6.4 



.391 



.68 



6.3.5 



55.4 









.15 



6.3.8 



57.1 



6.7 



.379 



.66 



64.2 



54.8 



29.626 







.20 



64.0 



56.8 



7.2 



.368 



.64 



65.4 



63.8 









.25 



62.3 



56.9 



5.4 



.390 



.72 



67.2 



54.3 









.30 



62 6 



57.1 



5.5 



.393 



.72 



69.8 



53.2 









.35 



62.8 



56.8 



6.0 



.381 



.68 



71.6 



53.2 









.40 



63.1 



57.0 



6.1 



.385 



.69 



72.4 



53.0 



29.626 







.45 



63.0 



56.1 



0.9 



.3.59 



.64 



73.2 



53.8 









.50 



63.1 



56.6 



65 



.373 



.66 



73.fi 



54.2 









.55 



63.1 



50.8 



6.3 



.378 



.67 



73.8 



54.8 









G.OO 



63.6 



57.0 



6.0 



.378 1 



.66 



73.5 



55.0 









.05 



04.1 



57.1 



7.0 



.376 



.65 





5-5.4 



29.626 



SWbS 



1.2 



.10 



64.3 



57.3 



7.0 



.380 



.65 





55.2 









.15 



64.1 



.57.1 



7.0 



.370 



.65 



76.4 



55.2 









.20 



64.8 



57.5 



7.3 



..381 



.64 



78.2 



64.8 









.25 



65.3 



57.6 



7.7 



.381 



.62 



76.4 



51.6 









.30 



65.3 



57.5 



7.8 



.374 



.61 



75.6 



51.0 



29.626 



SWbS 



0.8 



The dry and wet bulb thermometers were the Observatory 

 Standard,s in thcir_u,sual pcsition. 



The thermometer for solar radiation was a mercurial by 

 Watkins & Hill, its bulb covered with a coating of lamp-black 

 dissolved in spirits of wine, and freely e.'iposed to the sun'.s rays. 



The usual thermometer for terrestrial-radiation was employed, 

 its bulb in the focus of a polished planisphere, and protected 

 from the sun's direct rays. 



In considering the meteorological effects produced by the ab- 

 normal extinction of the sun's heat in an eclipse, it is evident 

 that these effects are always mixed up with the ordinary changes 

 that arc produced by the cver-varj'ing conditions of the atmos- 

 phere and the other causes that determine the meteorological 

 conditions at a given time and place, and it is only by a com- 

 parison of results obtained at numerous statidns that those 

 latter can be eliminated. Still, an examination of even the 

 few sets in the preceding tables will furnish several points of 

 interest. Thus, at JMontrcal, the ri.sc of the barometer is 



marked and steady ; at Toronto, on the contrary, the barometer 

 sank during the early part of the eclipse, and then, after a 

 slight rise, remained perfectly steady during the latter half of 

 the period, showing that the rise at Montreal was not a pheno- 

 menon peculiarly connected with the eclipse. Again, at Pres- 

 cott, the tension of aqueous vapour fell somewhat suddenly 

 about ten minutes before the annularit}-, reached its lowest 

 point five minutes after the end of the annularity, and then 

 increased during the remaining period ; at Toronto, the changes 

 are more irregular, but indicate, on the whole, a descent 

 throughout ; while at Montreal the same fact may be noted, 

 though with still greater irregularity. 



The following abstract gives the values of this tension for the 

 three places at the times of beginning and end, and greatest 

 obscuration, and also the mean values for the first and latter 

 halves of the duration of the eclipse : — 



Tension of Vapour 



Prescott. 



Toronto. 



Montreal 







Beginning of Eclipse 



0-304 



0-459 



0481 



Middle 



■276 



•393 



•404 







End 



•304 



•376 



•435 







Mean of First Half 



•293 



•418 



•489 







Mean of Latter Half. 



•289 



•360 



•457 



In the total eclipse of 1842, it was noticed at Perpignan 

 that a strong dew was deposited after the total obscuration, 

 falling in drops from the leaves, the explanation of which is 

 clearly that the temperature of the eaith had been more reduced 

 by radiation than that of the air by the deprivation of the sun's 

 rays, and to such an extent as to reduce the contiguous strata 

 of air below the dew-point temperature, and thus cause them 

 to deposit dew. It is, therefore, a point of interest to examine 

 if, during the eclipse, any increase of humidity can be detected 

 in the atmosphere, which can fairly be traced to such a cause. 

 An examination of the tables shows that none .such can be de- 

 tected, the humidity decreasing at Toronto and increasing at 

 Prescott with about equal steadiness, while at Montreal the 

 changes are less regular, but give an increase in the latter half 

 of the period over the former. 



As might be expected, the effect of the deprivation of the 

 sun's heat on the temperature of the air is decisively manifested 

 by the thcrmomctrieal observations, of which those at Toronto 

 and Prescott, having been made by standard instruments and 

 with all possible precautions, may claim a certain degree of 

 precision ; those at ^Montreal are less available by reason of 

 the unfavourable nature of the day. As regards the march of 

 the ordinary dry bulb thermometer, two causes are involved, 

 at first conspiring but afterwards opposing each other, namel}', 

 — the ordinai'v diminution of temperature by the decline of 

 day, and the gradual extinction and subsequent restoration of 

 the sun's ra3s. In the earlier interval of the period cf eclipse 

 jjoth combine to lower the ten;perature, but, later on, the dc- 

 .scent of the sun and the gradual enlargement of his visible 

 disc produce opposite effects, and we arc thus ])repared to find 

 the fall of the thermometer not aftcrw.-irds ciimpen.s;ited fur bj' 

 the subsequent rise. At Prescott, tlie fall during the eclipse 

 was G°^5, and the subsequent rise only 0°^S ; at Toronto, these 

 quantities were 4°^G and 3°^0; at Kingston 8° and ;>°. Thq 



