1+ S, It. Williams — N'ew Typt of Mercury Air-Pump, 



niann and Gaede pumps. In this locality the chain ami bucket 

 pump is used very extensively in lifting water. In consider- 

 ing the principles involved, it occurred to me that possibly a 

 mercurial pump might be constructed on the principle of the 

 chain and bucket water-pump which would involve all of the 

 conditions required for efficiency. The object of this paper is 

 to describe such a piece of apparatus. 



Fig. I is a vertical section of the pump devised. Over the 

 sprocket wheels $„ s 3 , s t , s t and s 5 , an endless chain runs to which 

 are attached any desired number of buckets. This chain and 

 bucket system is housed in the cast-iron base, B, the two tubes, 

 T, and T 2 , and the small chamber, D ; s is a drive wheel 

 actuated by a crank or motor. Mercury is poured into the 

 chamber, C, until it is nearly full. This fills all the passages 

 below where the sprockets, s 2 , s 3 , s t , and s 6 , are located. The 

 machine is then ready for use. The vessel to be exhausted is 

 attached to the tube, O. The crank is turned so that the 

 buckets in the tube, T 2 , rise. As they ascend they carry them- 

 selves full of mercury, which on passing over the sprocket s, 

 is dumped out and runs down either T, or T.,. On descending 

 through T,, the buckets are inverted and now carry themselves 

 full of air, which is imprisoned in the buckets when they 

 reach the level of the mercury. This is carried on down 

 around sprocket s 2 , and when the buckets pass under s s they 

 are turned with the top up, which permits the air to escape, 

 and which rises up through the mercury in chamber C, and so 

 passes to the outside atmosphere through the opening in the 

 cover, L, where the drive chain passes from s t to s 6 . The buck- 

 ets then pass on around s 4 and s b to repeat the operation. As 

 the exhaustion advances the mercury rises higher and higher 

 in Tj and T 2 until it stands at barometric height, for instance, 

 at the level indicated by the dotted line a — b. In order to 

 take care of what extra mercury rises in the barometric tubes 

 Tj and T 2 , the chamber, C, is recessed out in the casting B. 



Instead of the sprocket s e and crank, a pulley may be 

 attached and the pump run by a motor. A neater but more 

 expensive form of construction, perhaps, would be to replace 

 the drive chain with a shaft and bevel gearing. In construct- 

 ing this pump I have made the base B of cast iron and the 

 tubes Tj and T 2 of boiler tubing, while the chamber D is also 

 a casting galvanized over on the outside to insure that it is air- 

 tight. It will be noticed that only the chamber B and the 

 tubes T„ and T 2 need to be air-tight, as the bottom of the tubes 

 are sealed off just as in the ordinary barometer tubes. 



The speed of the pump in exhausting is limited only by the 

 rate of diffusion of the gas through the tube O from the vessel 

 being exhausted. The pump will exhaust to X-ray vacua. 



