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VI. Underground Temperature at Oxford in the Year 1899, as determined by 
five Platinum-resistance Thermometers. 
By Arthur A. Rambaut, HI. A., D.Se.., Radcliffe Observer. 
Communicated by E. H. Griffiths, F.R.S. 
Received May 17,—Read June 21, 1900. 
[Plates 1, 2.] 
Description of the Apparatus and Mode of Reduction of the Observations of 
Ea rth 1 e mpci n tu res. 
The instruments with which the earth-temperatures given in this paper were 
observed, were five platinum-resistance thermometers of the Callendar and Griffiths 
pattern,* made by the Cambridge Scientific Instrument Company. These were 
purchased by the late Mr. Stone, and were placed in position under his direction 
shortly before his death. 
The method of platinum thermometry seemed to be particularly suitable for this 
class of work, on account of the immunity it enjoys from certain errors attending 
the use of the long-stemmed mercurial or spirit thermometers ordinarily employed 
for underground temperatures. 
A higher degree of accuracy might, therefore, reasonably be expected, and the 
discussion which follows of the first complete year’s observations at the Radcliffe 
Observatory shows, I think, that this anticipation has been justified. Some 
discrepancies between theory and observation no doubt appear, but they are of a 
character which seems to indicate a difference between the assumptions on which 
the theory is based and the conditions actually prevailing in the stratum of gravel 
in which the thermometers are buried, rather than thermometric errors affecting 
the observations themselves. 
The thermometers are inserted in undisturbed gravel, the first four lying one 
under the other, in a vertical plane beneath the grass of the south lawn, and within 
a few feet of the Stevenson screen in which the dry and wet bulb, and the maximum 
and minimum, thermometers are suspended. 
In order that the thermometers might lie in practically unbroken ground, the 
following method of placing them was adopted. A pit was dug at the edge of the 
* See the Cambridge Scientific Instrument Company’s “ Descriptive List of Instruments,” page 20. 
2 H 2 22.11.1900 
