58 L. Waldo— Papers on Thermometry. 
We have not yet received from the Kew Observatory any 
further statement as to what the chemical constitution of the 
glass used in ‘“‘ Kew 578” and “ Kew 584” is, than that they 
are blown from ‘“ Powell’s best flint glass.” This does not 
enter into the subject of our present paper and will be discussed 
in a subsequent one in connection with the comparison of the 
Kew standards with the standard thermometers of the Kaiser- 
liche Normal-Hichungs-Kommission. 
he thermometers, Kew 578 and Kew 584, are almost exactly 
alike with the exception of their graduations. Kew 585 is so 
much longer and of so much larger tubing, that it was not thought 
wise to include it in the standard to be established between 0° 
and 100° C. The following is the description of these instru- 
ments. 
Designation. How Graduated. Length of 1°. sy came aN ban igigentetns 
Kew 578 — 9° to + 105° C, 3°46 mm 0°°5 455™™ 60™ 
Kew 584 + 14° to + 220° F. By es 1 455 ig Ore 
Kew 585 | — 34° to + 275°C. | 1°73 “ 1 618 T4 
Cylindrical Bulb. 
Designation. Length. Thsibes, Remarks. 
: Graduated at the Kew Observatory, 
Pew Oe ee ee { 1880. Filled in July, 1874 
“ ren Graduated at the Kew Observatory, 
mee SEG Ve ae sh { May, 1880. Filled in July, 1874. 
“ ‘i ade Graduated at the Kew Observatory, 
ache hea! WR “7 ; May, 1880, Filled in July, 1874. 
They are each provided with a chamber at the upper end for 
the purpose of calibration. The measured bulbs of similar 
thermometers broken at Kew, give, approximately, a thickness 
of the walls of the bulb of 0025 inch. With similar thermom- 
eters the has maximum depression of the freezing point 
observed after the boiling point, is found to be 0°17 C. 
The following pieces of apparatus were used in the investi- 
gation, and they will be referred to by the Roman numeral. 
I. The Crouch microscope comparator, elsewhere described,* 
provided with an eye-piece micrometer by Powell & Leland, 
and an objective of 1 inch equivalent focus. 
I air of microscopes provided with eye-piece microme- 
ters and objectives of 4 inches equivalent foci, by Beck. These 
microscopes can be adjusted so that their stages are in the same 
* Proc. Am. Acad. Arts and Sci., Bost., vol. xiii, 1877-78, p. 352. 
