( 224 ) 



scrowerl as ]. e. p. witli marino-olne into tlie cap aiul into the ovor- 

 pipe, and ai'tor lljis the joint has been soldered with tinnians solder 

 in order to shut up the soft marine-glue firmly while the seam is 

 protected from the action of the mercury. 



The fastening' of the steel caps to the glass capillaries which are 

 widened towards the ends requires special care (comp. the cementing 

 of thermometer-capillary, Proceedings May 30tli 1896, p. 41)'). It is 

 done as then by means of red sealing-wax, that answered the pur- 

 pose better than several other mixtures that have been examined 

 since that for this puipose. In addition to the precautions in the case 

 mentioned 1. c. we had to prevent the sealing-wax from having 

 contact with the steel capillary until all the air has escaped, as 

 else the passage for the air would be blocked up. which would 

 cause a defective closure. 



"We continued the pushing on of the cap under moderate heating 

 as when cementing the volumenometer cap (1. c. p.) until the sealing 

 wax became visible between the steel capillary and the glasswall. 

 In this way we succeeded in getting perfectly tight connections, 

 only the joint between the glasscapillary and the steelcapillary 

 would sometimes give rise to defects and as the reliability of this 

 joint is of great importance to the usefulness of the manometer 

 Ave are still trying to get a better connection. After the joints 

 have been maile the manometertube is ready to be tested by pres- 

 sure in order that we may detect leakages. In order to fill the 

 manometertube with mercury we cement a small thin-walled glass- 

 capillary the point of which has been scaled, on the end of the 

 steelcapillary which projects beyond through the overpipe, then we 

 exhaust the manometer by means of the mercury pump and the 

 point is broken off under mercury. By admitting air we then can 

 expel as much mercury as is desirable. 



Each manometertube is fastened on a separate board /^i by means 

 of 4 clamps k (comp. fig. 5) between cork and this boaid is screwed 

 on to a board /?2 which is fastened to the wall by means of fixing 

 it to a strip I. 



The T-pieces on the board on which the stopcocks are fastened, are 

 forged of steel and have been pierced afterwards. The high-pressure 

 stopcocks (the ordinary Leiden pattern) are also entirely made of steel 

 in order not to be attacked by the mercury which might accidentally 

 get into the horizontal connection-canals of the T-picces; they have 



1) Comm. of the Pliys. Lul), at Leiden ISÜO. N". 27, ]). S. 



