JULY, 343 



which the rising luminary passes ere his full form appears in 

 sight, is attended with emotions like those which might be 

 supposed to attend us at the actual opening of the gates of 

 Paradise, We return home, after this ramble, with a heart 

 warmed by new love for the beautiful objects of nature, and 

 with all our feelings so harmonized by the sweet influences 

 of morn, as to find increased delight in the performance of 

 our duties and the exercise of our affections. 



Enteral Boticts. 



Self-Registering Hygrometer. — The Honorary Secretary of the 

 Torbay Horticultural Society has invented a very useful instrument for 

 gardeners, which he calls a Self-Registering Hygrometer. 



It is needless to say that the hygrometrical condition of the air is as im- 

 portant to the horticulturist as the thermometrical ; and it is desirable that 

 the instruments used in determining either humidity or temperature should 

 be self-registering, in order that we may ascertain their condition, not only 

 at the moment of observation, but also their fluctuations during any preced- 

 ing period. 



Self-registering thermometers have long been in general use, with the 

 most beneficial results, but no self-registering hygrometer has hitherto been 

 constructed, and those which have been adopted for time observations have 

 either been very imperfect, or not sufficiently simple and inexpensive for 

 horticultural purposes. ' 



The new instrument which Mr. Vivian recently submitted to the Horti- 

 cultural Society, and from whose report this account is chiefly taken, is a 

 combination of Leslie's wet-and-dry-bulb hygrometer and the differential 

 thermometer, with steel indexes, which may be adjusted either by gravita- 

 tion or the magnet. The degree indicated by the spirit or index in the 

 tubes is the amount of difference between the temperature of the air and 

 evaporation ; when it stands at zero (0) the air is completely saturated, and 

 the sensible humidity of the air becomes less as this difference increases. 

 Thus, observes Mr. Vivian, in an orchid house the instruments should never 

 register more than one or two degrees, whilst ericas will require eight or 

 ten degrees. 



For meteorological purposes, the actual humidity may be readily ascer- 

 tained from Mr. Glaisher's tables, or the dew point may be approximately 

 deduced by doubling the amount of difference between the wet and dry 

 bulb. For instance, if the reading of the hygrometer is five degrees, 

 whilst the thermometer is fifty degrees, the dew point will be forty-five de- 

 grees, below which, fog, rain or the precipitation of dew will occur. 



