216 Proceedings of the British Association for [Sept, 



.20. Mr. Snow Harris, on Thermometric Observations. He 

 produced a report of hourly observations, conducted at Ply- 

 mouth, and illustrated it by diagrams, representing the 

 mean daily curves of temperature at different periods of the 

 year. He compared them with similar observations made 

 at Leith. 



21. Mr. G. Jerrard, on the Solution of Algebraic Equations. 

 An account of these researches was given by Professor 

 Hamilton. 



22. Professor Phillips presented the third report on the 

 fall of rain, in continuation of his former reports. It fully 

 confirmed his remarkable results announced last year to 

 the Association, viz. that less rain falls, in proportion to 

 the height from the ground ; and extended them so as to 

 lead to some general theoretical views. 



Mr. P. proposed that the Association should either pro- 

 vide, or recommend members to procure rain-guages, and 

 have them placed at different places, at different heights 

 from the ground, not to exceed 150 feet, which he appeared 

 to think quite sufficient for the collection of data, to enable 

 calculations to be made to ascertain the quantity of rain 

 which would fall into a guage at any height. This sug- 

 gestion led to some discussion in relation to the dew 

 which would be collected in the guage along with the rain, 

 and thus would vitiate the result. It was also stated that 

 radiation from different places had a great influence on 

 the formation of vapour. Thus, the Sugar-loaf and Howth 

 mountains are frequently capped with clouds when the 

 Dublin mountains are quite clear, hence the necessity of 

 care being taken in placing the guages. It was also stated 

 that there is a quantity of rain discharged from a variety 

 of those clouds known by the name of nimbus ^ which 

 never extends to within a considerable distance of the 

 ground. These clouds, which do not extend to the ground, 

 are well known. The rain falls into the lower air, and is 

 absorbed by it ; the latent heat for the solution being fur- 

 nished by the lower stratum of air, or by radiation or reflec- 

 tion from the ground itself. The guages, arranged as pro- 

 posed, would be no measure whatever of rain of this kind, 

 and would, consequently, furnish erroneous results for 



