Mr Stevenson on (he Defects of Bain-gauges', IS 



able also that there should be a small rim \i\\ or ^tb inch 

 high fixed to the horizontal plate. 



Fig. 2. 



The following very serious sources of error may be said to 

 be nearly annihilated by the instrument above described, viz. 

 the well known eddy resulting from the obstruction offered by 

 the rim and funnel sides, resilience and dispersion of the rain 

 and hail drops from the rim and funnel sides of the gauge, 

 and similar resilience from the ground into the gauge.* 



Edinburgh, January 5. 1042. 



Since the above was written, answers have been received 

 from several of the light-keepers of the Northern Light-houses 

 to queries sent them relative to the effects of high wind on 

 gauges. Besides their other duties the keepers daily register 

 the results of the rain-gauge, one of which was placed at each 

 station by order of the Commissioners of the Northern Light- 

 houses many years since, who justly considered that in this 

 way they would be enabled, in the event of a shipwreck tak- 

 ing place, to ascertain more exactly the state of the weather, 

 and at the same time render a valuable acquisition to science. 



The answers alluded to are of considerable interest and 

 value, consisting of the observations of forty intelligent men, 

 on the effects of wind in connection with rain, but I shall 

 only give a few of the results obtained. 



The observations were confined to one month, and were 

 made by forty-four keepers ; but owing to the late gales, re- 

 turns have been received from only forty of them, of whom 

 four considered that the accuracy of the gauge was not af- 

 fected by the wind, while thirty-six considered that it was. 



* I regrot that I have not as yet been able practically to compare the re- 

 sults of this form of instrument with those commonly in use ; but in a hail- 

 sliower to which the gauge was exposed, the surrounding bristles appeared 

 efficiently to answer the pni-pose for which they were designed. 



