On Night-Frosts. 29 



The torches hâve passed tlirough several important stages of improvement 

 since they were introduced by me. 



Tlie ftrst experiment was made with torches consisting of a mixture of 

 mud (well mouldered white moss), resin and pulverized coal, in the form of 

 tube-cylinders, 20 cm in height, 13 cm in diam. Avith an opening of 4,5 to 

 4,7 cm. 



The mixture was made with a crane or with a machine for turf-tubes 

 (bm-ning tui'f). With the aid of a very little quantity of petroleum thèse tubes 

 could be kindled quite easily, being well dried. The price was about 6 pennis ' 

 a torch. After a gi-eat number of experiments the proportions of the mixture 

 were fixed. 



These torches were yet in want. 



They could not be placed in the field and remain there all the time frost 

 was threatening, because they might become too moist in case of rain. They 

 must always be put under roof again if not burnt. 



It must be conceded that this want might occasion much uunecessary work 

 in certain summers. 



Proceeding from the quality peat or mud has to carbonize, if a certain 

 quantity of it is heated in one point enough to cause burning, it was thought 

 advisable to make tubes of well mouldered mud which had passed through the 

 crane tmce and to kindle them in a special way. Several trials to do it with 

 petroleum in différent quantities did not succeed, for mud is a bad conductor 

 of heat and the petroleum, with which a diy tube has been moisted, burns 

 without heating it long enough to produce carbonizing. Even if the tube of 

 mud was altogether moisted with petroleum and kindled, the oil burnt in a 

 flame without making the tube carbonize. Therefore special kindling-cylinders 

 were constructed, the composition of which was fixed, many experiments having 

 been made. 



Thus, the frost-torches, or torches of tliis new construction, consist of tiibes 

 of well dried mud and of kindling-cylinders, which can be inserted into the tubes. 



If the tubes of mud are well dried, they may be placed in the field, which 

 is to be protected and remain there all the time frost may be expected, or until 

 they are used, for the rain affects only theh- surface and they dry very soon. 



The diameter of the kindling-cylinder is 4,5 cm, its height 3 cm with an 

 opening of 1 cm. When moistened with a little petroleum, the kindling cylinder 



' Penni = the French centime. 



