508 Transactions of the L.ondon Horticultural Society, 



Register of Geothermometers in the Garden of the Horticultural Society in the 

 Month of January, 1838. 



January 1 



1 Foot deep. 



2 Feet deep. 



January 17 



1 Foot deep. 



2 Feet deep. 



46 



46 



34 



38 



2 



46 



46 



18 



34 



37^ 



3 



45 



46 



19 



33i 



37 



4 



42 



43 



20 



33 



37 



3 



42 



44 



21 



33 



35 



6 



41 



44 



22 



33 



35 



7 



40 



43 



23 



33 



36 



8 



39 



41 



24 



33 



36 



9 



37 



41 



25 



33 



36 



10 



36 



40 



26 



33 



35 



11 



36 



40 



27 



33 



35 



12 



36 



40 



28 



33 



35 



13 



35 



39 



29 



33 



35 



14 



35 



39 



30 



33 



36 



15 



34i 



38 



31 



33 



35i 



16 



34 



38 









" It will doubtless have been remarked, that in the previous observations, 

 it has been assumed that the destruction which took place among plants 

 was owing to the intensity of the cold on the morning of the 20th of January. 

 I am aware that, in the opinion of some intelligent observers, it was not so 

 much the excess of cold which produced death, as the subsequent thaw, 

 either on the 22d of January, when the thermometer rose to 46*^, or in the 

 end of the month, and in February. This opinion seems to be formed upon 

 the absence of any appearance of death in some cases till that time, and also 

 upon the well known fact, that frozen vegetables and trees, suddenly thawed, 

 will die, while they recover, if the temperature is raised by slow degrees. 

 The absence of the appearance of death in certain plants, till some time after 

 it actually takes place, is perhaps owing to the decomposition, which is 

 induced by the intensity of cold, either being suspended so long as they 

 remain frozen, or proceeding very slowly in cold weather. That it really 

 was the excessive cold, which in general produced destruction, may be con- 

 cluded from this ; that such effects as we experienced last winter are not 

 observed in milder winters, in which rapid thaws succeed severe freezing; 

 and, because it seems certain from what we know of plants, that it is not 

 the mere act of freezing, or unfreezing, that destroys vegetable life ; it is 

 necessarj' that the amount of freezing should reach some unknown point, 

 which seems to vary in different species. Dr. NeufFer has shown (Edin. 

 New Phil. Journ., 1830, p. 141.), that trees are frozen within certain hmits 

 without apparent injury. In some trees, he ascertained that the temperature 

 was lowered to +5°, or even to -\-l^°, without the power of vegetation 

 suffering; so that the reduction of vegetable tissue by cold into that state 

 which is succeeded by an immediate decomposition of the organic parts, varies 

 in different species according to their pecuhar nature. 



" In considering the various circumstances alluded to in this paper, I was 

 naturally led to inquire into the exact manner in which the death of plants 

 is caused by cold. Very little, however, is to be learned upon this subject 

 from the writings of physiologists. 



" The common opinion is, that frost acts mechanically upon the tissue of 

 plants, by expanding the fluid they contain, and bursting the cells or vessels in 

 which it is enclosed. 



" M. Gceppert, of Breslau, in a paper, originally read at the meeting of 

 German naturalists at Leipsig in 1829, briefly abstracted in OJcen's Isis for 

 1830, p. 497., and translated in the Edinhurgh Journal of Natural and Geolo- 

 gical Science for 1831, p. 180., denies that this supposed laceration of vege- 



