228 Scientific Intelligence. [Sept. 



great that it may be extracted from them economically for the 

 pmposes of sale. — (Gilbert's Annalen, Ixiv. 161.) 



IV. Self-registering Rain-Giiage. 



Mr. Donovan, Professor of Chemistry, Materia Medica, and 

 Pharmacy, to the Apothecaries' Hall of Dublin, with whose 

 merits as a chemist and philosopher my readers are well 

 acquainted in consequence of his very valuable work on galva- 

 nism, and his important chemical papers, of which due notice 

 has been given in the Annals of Philosophy, has just completed 

 a very curious and ingenious rain-guage possessed of the follow- 

 ing properties : 



" This machine is calculated to keep an exact register of the 

 quantity of rain that falls during any period of time in the absence 

 of the observer. Nothing more is required than to put a card 

 into the machine and wind it up. At the end of every week, the 

 card is to be removed, and a new one put in : on it will be found 

 registered the following particulars : 



" It will show at what precise hour and minute of the day, 

 and upon what day, the first cubic inch of water fell during any 

 series of weather. 



" It will show how many cubic inches of rain fell during the 

 whole week, and the precise hours at which each fell, what day 

 of the month, and whether it was night or day. Hence we have 

 also an exact measure of the heaviness of the showers. 



" It will show w'hen the rain commenced (at least so as to be 

 worth noting), how long it continued ; what intervals there were 

 of tolerably dry weather ; and when the rain ceased. 



" The descent of each inch of rain will also be announced by a 

 bell, which will act as a notice at night when access cannot be 

 had to the detailed account on the register. The examination of 

 the register card need not be weekly ; it may be consulted at any 

 time. 



" The machine will tell not only the individual cubic inches of 

 rain with their times, but it will show the total quantity at one 

 view. 



" At the end of the week, the card is to be put on a file, and 

 thus, without any trouble of writing or watching, may be kept a 

 precise register, that can at any time be consulted with ease, of 

 the weather with regard to rain. 



" The machine can be adjusted in such a manner that instead 

 of cubic inches of rain it will register its results in ounce mea- 

 sures, which, being the sixteenth of a pint, would be more 

 generally appreciated. 



" It requires winding once a week, and a new card ; this is all 

 the trouble it gives ; but it may be constructed very easily so as 

 to require these operations but once a month. It is not liable to 

 go out of order ; for however complicated its functions may 

 appear, its individual parts are simple." 



