HAILSTONES, RAINDROPS, AND SNOWFLAKES. 165 



warm saturated air the ether did not reduce the temperature 

 of the air and the vapour it contained much below 32°, and 

 consequently, when the water spray was added, the water 

 was only partially frozen. 



I subsequently improved the apparatus so as to be able 

 to regulate the supply of water and ether to the condition 

 of the air. 



The Ajjparatus. 



This is shown in the accompanying sketch (p, 166), It 

 consists of a brass tube half an inch in diameter, one end 

 of which is connected with bellows capable of maintaining a 

 constant pressure of about eighteen inches of water ; on the 

 other end of the tube is a cap, over the end of which is a flat 

 plate or diaphragm having a central opening an eighth of 

 an inch in diameter, which forms the aperture for the blast. 

 Entering through the sides of the main brass tube are two 

 small brass tubes which reach to within half an inch of the 

 plate, and into the ends of which are sealed fine glass ca- 

 pillary tubes, the glass being very thin ; these protrude just 

 through the middle of the aperture, the one about one six- 

 teenth of an inch and the other one thirty-second. Through 

 these tubes the water and ether are separately introduced 

 into the blast to form the spray; and it is mainly on the 

 adjustment of these tubes that the efficiency of the appa- 

 ratus depends. It is essential that the ether-tube should 

 be slightly the longest ; otherwise the ends become stopped 

 with ice ; and I find it better that the ether-tube should be 

 somewhat larger than the water-tube. The bore of the 

 tubes must be very small : but this is not sufficient ; for 

 unless the glass is very thin the spray will not be finely 

 divided. Both the ether and water are forced through the 

 tubes from bottles by connecting the interiors of these 

 bottles with the bellows ; and the quantities of ether and 



