XXXVll 



is placed about 18m. from the ground, without protection above or around 

 it, and the general conditions of exposure are nearly equal to those under 

 which the temperature " on gi'ass " is usually ascertained. On the other 

 hand, there is no thermometer in use at the Barracks at present 

 for recording the temperature " on grass," nor is there any place available 

 for the purpose. The maximum and minimum thermometers are in- 

 tended to record the temperature of the air under definite conditions of 

 protection, and are kept, as nearly as present circumstances allow, under the 

 conditions prescribed for all the meteorological stations in the inter- 

 colonial system. They are new instruments by Negretti and Zambra, 

 and as they were obtained from Mr. Ellery, it is superfluous to say that 

 they supply a better standard than is obtainable elsewhere in the colony. 

 Their position, pending the completion of the instrument shed, is of course 

 not satisfactory, and they will probably register both a higher and lower 

 temperature when placed under it than they do now ; but it must be 

 remembered that the temperature of the air, as taken at a meteorological 

 station, is a very difFei^ent thing from the temperature " on grass." My 

 own observations have necessarily been so irregular that they are of little 

 value ; but I believe that the lowest temperature yet noted in the colony 

 was registered by a thermometer which I placed on the top of Mount 

 WeUington several years ago, and which gave 16deg, as the minimum 

 temperature for two consecutive winters. The minimum "on grass" in 

 Hobart during the same period was 24deg. ; but, for the present exceptional 

 season, a record of 21deg., as the minimum temperature, is probably not 

 far from the mark. But no meteorological statistics can be satisfactorily 

 registered at Hobart until the station is properly equipjjed, and favourable 

 conditions of observation permanently and effectually secured. Since 

 writing the above I find that Mr. Shoobridge records as the minimum 

 temperature of the air at New Norfolk, on the night of the 28th July, 

 29deg.; and on the following night 26deg.; a result which, if I may judge 

 from experience of the winter temperature at the two places, agrees pretty 

 closely with that obtained ao the temporary station in the Barracks. 



On the conclusion of the reading of the ;^)aper, Mr. Grant observed that 

 Commander Shortt must have chosen i:' unfortunate position for his 

 thermometer, the day temperature throughout the whole of the 30th 

 July having certainly been below the freezing point, as proved by the 

 frozen condition of the gi'ound, and the forming of ice on tubs placed 4ft. 

 above it, where sheltered from the direct solar rays. Such temperature, 

 therefore, would probably have been much lower during the preceding 

 night, and was proved to be so by the observations of Messrs. Hall and 

 Whall. He understood that Captain Shortt's thermometer was placed under 

 a deep verandah, and a worse place than an ordinary verandah could 

 scarcely be selected for observing the air temperature. The usual position 

 for this instrument is at the back of a light screen of trellis work or louvre 

 painted white, and with a top covering which protects it from the direct 

 sunlight, but allows the free circulation of the air around, and it should 

 be at such a distance from every other object as not to receive heat 

 therefrom. Under a verandah the temperature of the partially stagnant 

 air, increased by the heat radiation of all surrounding objects, especially of 

 the house, would alone be obtained, and doubtless difi"er many degrees 

 from the true air temperature correctly taken. In a long course of 

 practical experiments and observations he had not found much difference 

 in the minimum readings were the thermometer placed only 9in., or 

 several feet above the ground, whether covered or uncovered, if the roof 

 were simply a shade ; but there was a considerable difterence on a clear 

 night between the readings of an instrument placed on the grass, or not 

 more than Sin. above it, of a wet bulb, and of a dry bulb thermometer ; 

 the wet bulb reading showing an intermediate temperature between the 

 other two. He did not think that in Hobart the extreme difference would 



