ON THE OBSERVATORY AT KEW. 115 
Prof. de Souza desired an absolute standard such as is at Kew. Solargeatube 
could neither be filled by the ordinary method, nor, of course, transported 
full, The course taken was therefore to learn at Kew how to perform the 
filling process by Mr. .Welsh’s method, so as to put it in practice at Coimbra. 
The experiment was made with two glass tubes of ordinary size, of which 
Prof. de Souza filled and closed one in the proposed manner, and Mr. Casella 
the other, with equal success. 
Prof. de Souza then ordered from Mr. Casella two tubes of large dimension, 
very clean and the air exhausted, with the cistern and all the appurtenances of 
the barometer to be made with one of them. If he succeeds, according to his 
hopes, as he did at Kew, Coimbra, he says, will possess an absolute standard, 
which will be the standard for Portugal as that of Kew is for England. But 
he proposes not to order the cathetometer until the tube is actually filled and 
raised into its proper position, He then gives the list of the other meteoro- 
logical instruments, all verified at Kew. 
“A standard thermometer graduated in divisions of 0-2 Centigrade. It 
was one of the best old tubes in the possession of the Observatory, only 
wanting the graduation, which was skilfully performed under my sight by the 
young George Whipple, assistant at the Observatory. 
** Two psychrometers with divisions of 0-5 Centigrade. 
‘A maximum registering thermometer on Professor Phillips’s principle. 
* A minimum registering spirit thermometer. 
‘A minimum registering mercurial thermometer; a recent invention of 
Mr, Casella, which was tried at Kew with a good result, and may be advan- 
tageously substituted for the spirit thermometer, of which the defects have 
long been recognized by meteorologists. 
** A Herschel’s actinometer. 
‘* A spirit thermometer for registering terrestrial radiation, with a suitable 
parabolic mirror, 
«Two rain-gauges. 
‘‘ A vaporimeter with the corresponding pluviometer.” 
With the above, and a pluviometer and hygrometer of Regnault, and an 
anemograph by Salleron belonging to the Cabinet de Physique at Coimbra 
(which requires to receive some modifications), Prof. de Souza considers 
that an equipment is provided for immediate work, contemplating eventually 
the addition of “apparatus for the continuous registry of barometric and 
thermometric variations, the cost of which will be under £120.” 
The continuous registry of atmospheric electricity by the photographic 
process must be given up for the present: Professor Thomson’s electrometer, 
excellent in principle, leayes, however, somewhat to be desired in practice. 
Prof. de Souza examined the one at Kew with great attention, watching its 
march carefully, and afterwards haying it taken to pieces ; and he is of opinion, 
as is also Mr. Stewart, that slight modifications would obviate some of the 
defects to which it is liable. 
Mr, Beckley has drawn a plan and elevation for the Observatory at 
Coimbra, which is submitted to the Council of the University: it provides 
both for the instruments which have been ordered, and for such as may, it is 
hoped, be subsequently acquired, these being a barograph and thermograph ; 
and possibly hereafter a photo-heliograph for obtaining images of the solar 
_ Spots, especially with a view to their supposed relations to magnetic pheno- 
mena. The cost of a photo-heliograph would now be about £80. In afew 
years many improvements will probably be made in it, and meantime what 
is wanted for this particular object may be supplied by observations of the 
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