Feb. 22, 1872] 



NATURE 



327 



THEORELL'S PRINTING METEOROGRAPH 



SOME time since brief mention was made of the above 

 instrument (devised by Dr. A. G. Theorell, of Xybro- 

 gatan, Stockholm, Sweden— Nature, vol. iv. p. 466) — 

 with reference to its having been exhibited at the Lond.on 

 International Exliibition, 1S71. 



Being in possession of a detailed description of the 

 same, I have thought that a copy with additional remarks 

 may be of interest in the pages of Nature. 



I have no hesitation in saying that this instrument does 



not occupy the prominent position to which it is justly 

 entitled, neither do'' I think that it is so well known — 

 whether taken in the light of a wonderful piece of 

 mechanism, or of excellent workmanship— as it well 

 deserves to be. 



The following is a description of the instrument in 

 accordance with the original, excepting only that I have 

 made a few slight alterations in order to render it more 

 intelligible, the original having been, as I suppose, 

 translated from the Swedish language, and not well 

 expressed :^ 



ISl:!l!!l!!!!:l!!!!!!l:l!i!!:!!;!l!!!!!!!!!!!!l!!lilllitllliil!i: 



" Meteorological observations are by this instrument 

 delivered in tables printed on a slip of paper. Of the 

 fotir tabular columns \\iQ first gives the hours, the second 

 the temperature, the third the degree of humidity accord- 

 ing to August's method, and the fourth the atmospheric 

 pressure ; this last (atmospheric pressure) is given in 

 millimetres, but the first figure, being always a 7, is sup- 

 pressed. The degrees of the thermometer employed are 

 those of the centigrade scale, and negative degrees are 

 expressed by their complements to 100. 



" The registration takes place by means of electrical 

 currents, which are closed by contact between the mercury 

 in the various meteorological instruments and steel wires 

 that descend into their tubes. These steel wires are con- 

 nected, by means of levers and three vertical screws, each 

 with its respective system of brass wheels with numerical 

 type engraved on the edges, in such a manner that the 

 rotation of the wheels causes an upward or downward 

 motion of the steel wires, so that the point of the scale on 

 which the lower extremity of the wire is situated, is neces- 



