METEOROLOGY. 391 



measure is desired, or else for a few minutes to a sliglitly higher tem- 

 perature. {Nature, July, 1881, xxiv, 294.) 



Mr. Crafts commuuicates to the Paris Academy of Sciences, a i^aper 

 on the depression of the zero point of the mercurial thermometer. He 

 finds that the greater the interval between the temperature that has 

 produced a depression and that at which the thermometers are kept in 

 order to raise it again, the slower is the movement j he gives a table 

 by which the depression through heating may be estimated. {Nature^ 

 XXVI, p. 72.) 



Dr. Leonard Waldu suggests slight changes in the manufacture of 

 the Kew standaid thermometers as follows: 



1. The calibrating chamber at the top of the thermometer is now 

 made as in the figure, where cal> is the capillary column, which expands 

 at a into the calibrating chamber. Instead of being rounded off at d, 

 the capillary column is continued a short distance to 1). This causes 

 serious inconvenience in the transportation of the instrument, or in its 

 calibration, because a small particle of mercury readily detaches itself 

 from that in the chamber a, and once in 6, with a cushion of air between 

 it and the remainder of the column, nothing but heat will dislodge it. 



It does not require very great skill on the part of the glass-blower 

 to form the chamber a by means of the pressure of the mercury itself 

 against the walls of the capillary column. The glass-blower, as is per- 

 haps well known, can soften the finished tube at a, and while the glass 

 is in this condition the gentle application of the flame to the bulb will 

 force the mercury into the part at a, and the careful application of both 

 flames will then form a pear-shaped cavity of a form which will not 

 retain a particle of niercury, and is exceedingly convenient in use. 



2. It is often desirable to hang these thermometers in a comparator 

 or other place, and it would facditate this if a glass ring were attached 

 to the upper end, as is the case with ordinary chemical thermometers. 

 It is observed that the plane of this ring should be parallel to the 

 enameling in the tube. 



3. It is often convenient to know the kind of glass used in the tube, 

 and the date of filling. Something more exact than the commercial 

 name of the glass would be needed in stating the former, but both of 

 these particulars might with propriety be engraved on the tube. 

 {Nature, June 2, 1881, xxiv, p. 100.) 



H. T. Brown describes a new self-recording thermometer for reading 

 the approximate temperature of any region, which is telegraphed to the 

 observer by a system of electric connections. {Nature, xxiii, p. 464.) 



The London Meteorological Society, in March, 1882, erected thermom- 

 eters at the summit and base of Boston church tower, 270 feet high. 



