114 ON THE POSSIBILITY OF PBE VENTING DAMAGES BY FROST. 



counteract those which are of an injurious character. Care 

 must thus be taken that strong currents of cooled air are kept 

 oat from the lower parts of the field, etc. Local circumstances 

 have to guide all the measures taken, and a careful study and 

 thorough knowledge of the phenomenon is necessary for the 

 successful use of this remedy. 



We have already hinted at the fact that a misapplied remedy 

 often may be more injurious than the frost itself. We have 

 witnessed several instances when big fires kindled after the 

 freezing of the plants had taken place caused a too rapid thawing 

 and subsequently death. The samefires kindled half-an-hour earlier 

 would have saved the crop. 



We have full faith in the effectiveness of smoke as a frost- 

 preventive, but the methods have to be developed, and for that 

 purpose a co-operation of science and practice is wanted. 



On the principle of movements in the air as preventing 

 injurious effects of frost, several methods have been tried. The 

 Finns used to pass to and fro dragging a rope over the field, 

 thereby causing a wave-like movement of the straw which results 

 in a success, but this method is of course only possible on a 

 small patch. 



We have not been able to ascertain from the records whether 

 the Stiger Vortex gun has been used in connection with frost 

 experiments, but it seems to me that shooting over a field during 

 a night-frost would be successful through causing the air strata 

 to be mixed, and thereby efi'ecting a restoration to the field of 

 heat lost by nocturnal radiation. 



ON FORECASTING OF NIGHT-FROSTS. 



For the practical agriculturist who wishes to avert from his 

 crop the evil eftects of frost, it is of the greatest importance to 

 be able to interpret correctly the warning signs given by Nature 

 herself before a frosty nighc, so that the protective measures be 

 not needlessly precipitated. A night-frost never coines unawares, 

 and its forewarnings are fortunately sure and easily interpreted. 



Every meteorological handbook contains information on 

 this head, so we need not go into that question. As we said 

 before the occurrence of frost and the phenomena connected 

 therewith are however dependent on not only the climatic 

 conditions in general, but also on local circumstances. A 

 careful investigation of the frost question is necessary in every 

 country where frost occurs, and the scientists, both the 



