on the Radiation of Heat. 311 



" Les rayons solaires ont la mime force calorifque en hiver et en 

 Hi." 



" Resultat qui paraitra fort singulier, et que I'auteur regarde 

 comme la confirmation d'uneanciennehypothese de De Luc suivant 

 la-quelle la lumiere doit prodidre d'autant plus d'effet que son trajet 

 dans I'atmospkere a ete phis long." 



The observations were made with a thermometer, having its bulb 

 blackened vyith Indian ink ; but as we are not informed what were 

 the special precautions adopted to render them, in M. Gay-Lussac's 

 opinion, " wortliy of all confidence," it is impossible to return the 

 compliment of a rigid examination of them. 



M. Flaugergues, however, has arrived at one result, with which 

 M. Gay-Lussac cannot altogether bring himself to acquiesce ; it is 

 as follows : — " si les differences entre les deux thermom^tres sont 

 plus grandes par un temps calme que quand le vent souffle, cela ne 

 dependepas du plus prompt refroidlssement, que le mouvement del' air 

 doit amener dans I'instrunient expose an soleil ; c'est par uiie modifi- 

 cation particuliere de la lumiere qu'elle ne produit pas autant d^effet 

 calorifque lorsque I air est en mouvement." 



And now, how will it be supposed that the dissent from this opi- 

 nion is expressed ? Doubtless with some such strong language as 

 that adopted with regard to the unfortunate observations of Captain 

 Sabine and myself — " Ce ne serait qu'apr^s avoir oubli6 les notions 

 lesplus elementaires de physique qu'on pourrait se permettre de com- 

 parer immediatement entr'elles des observations faitesdans des cir- 

 constances aussi dissemblablcs." No such thing — thus politely 

 and delicately is the conclusion dismissed—" Cette singuliere 

 opinion n'ayant point re9u I'assentiment des physiciens, il serait 

 inutile de la discuter'ici." 



Verily it is a good thing to have been born on the right side of 

 the Pas de Calais ! 



But I have done — Mon. Gay-Lussac will excuse me, if I have 

 been betrayed into levity of expression. I have endeavoured to 

 answer his remarks somewhat in the same style in which they were 

 conveyed; if there be any bad taste m adopting such, in scientific 

 discussions, the offence will not rest with me. I again repeat that 



