THE 1?EE»-KEEPERS' REVIEW 



•> •> II 



Kt *J J 



In this second table the numbers 

 are chosen so that the dew-point 

 is practically 4 5° F. in all cases, as- 

 sumed as an average cellar tem- 

 perature. It appears that a given 

 amount of water given off by bees 

 at 9 6° F. creates a much lower 

 relative humidity (18 percent) 

 than the same quantity of water at 

 60° F. (58 percent) because the 

 warmer atmosphere is capable of 

 holding more water vapor and rela- 

 tive humidity is simply an expres- 

 sion of the percentage present com- 

 pared with all the atmosphere can 

 hold. However, to maintain a tem- 

 perature of 96° F. necessitates the 

 consumption of much more honey 

 and this in turn gives off much 

 more water vapor. Consequently 

 with a cellar temperature of 45° 

 F. we should expect much more 

 condensation in a colony with a 

 cluster temperature of 9 6° F. than 

 in one with a cluster temperature 

 of only 65° F., except that the in- 

 creased heat would tend to pro- 

 duce stronger currents of air in the 

 hive which might relieve the situa- 

 tion somewhat.* 



Since 9 6° F. is about brood rear- 

 ing temperature it is partly indicat- 

 ed why brood rearing during the 

 winter confinement may be highly 

 injurious, as it is usually held to 

 be. It may be stated that a cellar 

 temperature of 45° F. and a cluster 

 temperature of 60° F. might not 

 occur; the other temperatures used 

 in the table might well occur un- 

 der different conditions. 



In making determinations of re- 

 lative humidity it is necessary to 

 take into account the barometric 

 pressure but in any given locality 

 the changes of the barometer are 

 so small as to be negligible and 

 therefore need not be disciissed 

 here. In any event in using wet 

 and dry bulb thermometers the 

 conversion table nsed must be for 

 the right barometric pressure. 



A further word of warnine con- 

 cerning the use of wet and dry 

 bulb thf^rmometers may not be 

 amiss. To obtain accurate results 

 the air must be moving past tbe 

 bulbs at the minimum rate of 15 

 feet per second and if this is not 



* L,at>iam, 1907, Olpaninss in Bpg Cul- 

 turp XXXV, DD. 1270-1272 advises lar.sre 

 entrances to permit the escape of ^vr.ter 

 vapor in damp cellars and the restric- 

 tion of t'le entrance to retain moisture 

 in dry cellars. 



occuring naturally the thermome- 

 ters must be whirled at a corres- 

 ponding rate. Unless this is done 

 the readings are entirely v/orthless. 

 Great care must be taken not to 

 read the wet bulb thermometer un- 

 til it registers as low as it will fall. 

 It is therefore obvious that wet and 

 dry bulb thermometers liung in the 

 bee cellar and not whirled gives 

 no reliable data as to the relative 

 humidity of the cellar. Many bee- 

 keepers thus use them incorrectly.* 

 How Moistuie E.scapefs From the 

 Hive iu Winter 



During the summer when nectar 

 is being ripened into honey great 

 quantities of water leave the hive 

 in the form of water vapor. During 

 this period the hive is being well 

 ventilated by fanning bees so that 

 the atmosphere is changed rapidly 

 and, being warm, is capable of 

 taking up more moisture than is the 

 atmosphere of the cellar. In winter 

 when the bees are in a cluster this 

 ventilation by fanning does not 

 occur, or perhaps we should say, 

 should not occur. The amount of 

 water that must leave the hive is 

 much less than in summer but on 

 the other hand it either must pass 

 out in air set in motion by changes 

 in temperature or will condense on 

 the frames, combs and hive and 

 possibly run out by gravity. 



If the atmosphere of the bee 

 cellar is heavily charged with 

 water vapor as is frequently the 

 case, that within the hive must be 

 saturated. The additional water 

 produced by the bees will therefore 

 condense and run out the entrance. 

 It frequently happens that the air 

 outside is capable of taking up this 

 moisture again by evaporation, so 

 that there may be no water visible 

 except within the hive, most often 

 on the cover, and possibly also on 

 the bottom board. 



If the wooden cover of the hive 



* In Hutchinson'.s Advanced Bee Cul- 

 ture (4th Kd. 1911) there is a valu- 

 able chapter on humidity in cellars but 

 the author fails to explain the proper 

 use of the wet and dry bulb thermom- 

 eters and his advice is tberefore open 

 to sei-ious ob.iection. If Hutchinson's 

 advice to make the instrument for meas- 

 urinjr humidity from two thermometers 

 is followed, it is imperative that care- 

 fully calibrated instruments be obtain- 

 ed and these can rarely be had in the 

 ordinary markets. Cheap thermometers 

 are the source of many errors in re- 

 cords of bee cellars. 



