HATCHING DUCK EGGS. 



87 



keep the •vacant rozvs in front, in which place the 

 thermometers, which hold at qq*-'. After the 

 twelfth day you will notice the temperature 

 rising, with the adjustment as you have held it: 

 it will now require less flame, and the adjustment 

 of the damper-valve will need to be altered a 

 little. The fact is the animal heat is now rising, 

 and if the machine is full of live germs it will 

 need close watching. Examine it the last thing 

 at night, or you may find the heat up to 105" or 

 more on the eggs in the morning, especially 

 the third week ; and if this occurs many will 

 suffer or die in consequence, not immediately, 

 but lingering along until almost the end of the 

 hatch, when they finally expire. After the third 

 week this danger is not so great, as the 

 animal heat remains about stationary, or declines 

 a little until exclusion begins, when it increases. 

 A temperature of 105° or 106'^ is desirable at 

 this time, and do not let it fall below 103° until 

 all are excluded. When the last one is dry, 

 open one of the doors about two inches and 

 securely fix it in this position, and let it remain 

 for twenty-four hours, so as to accustom them 

 to a slightly lower temperature before removing 

 them to the brooder. 



" The only cooling of the eggs that should be 

 done besides what they get during the daily 

 turnings, is during the third week, when they 

 should be cooled down daily till a thermometer 

 on the eggs in the drawer stands at about 90". 

 Under no circumstances cool any during the last 

 week. It may be argued that cooling from the 

 start is the natural process, which I admit ; but 

 we must refrain from practising it at any other 

 time than specified, because we cannot as quickly 

 restore the incubating temperature as the parent 

 bird. It often takes us several hours to accom- 

 plish what she succeeds in doing in fifteen 

 minutes after resuming her nest. 



" Ventilation is the next important question. 

 The most common and usual practice is to 

 ventilate to excess for chicken eggs, and add 

 still more to the duck tgg, because it is larger. 

 This is a serious mistake. In either case there 

 should be only sufficient ventilation to keep the 

 air in the egg-chamber respirably pure, and this 

 must be admitted in such a manner as to 

 produce no perceptible currents. A moving 

 body of air will absorb and carry away all the 

 available moisture it can gather, and its capacity 

 for moisture is increased in proportion to its 

 rise in temperature, and its velocity; hence fresh 

 air taken into the ventilating flues at a tempera- 

 ture of 65*^, even if laden to a high degree with 

 moisture, will on being heated to 103° have a 

 capacity for more, and will abstract it from its 

 surroundings until the tension is equalised. In 



this way the egg may be robbed of its moisture, 

 and the embryonic structure suffer in conse- 

 quence. The Creator has in His wisdom pro- 

 vided the amount of water necessary for the 

 proper growth and development of the embryo, 

 and also for any loss that may arise from 

 natural evaporation during that period. The 

 moment we attempt to take any from it by 

 any means whatever, we rob it of that which it 

 needs, and it suffers in consequence. Some 

 writers would have us believe that successful 

 hatching depends upon our ability to evaporate 

 the egg to a certain degree in a given time, and 

 even furnish us diagrams to guide us. A strong 

 healthy germ will utilise the entire contents of 

 the egg in its structural development, and the 

 waste products resulting will be cast off as 

 Nature provides. This is what should enlarge 

 the air-bulb ; any other means used to attain 

 this end are unnatural. Supply only the necessary 

 oxygen to sustain life, with the proper degree of 

 heat, and the fundamental conditions are secured, 

 and the moisture will take care of itself 



"A good incubator is very essential to success; 

 cheap machines, like cheap watches, are unre- 

 liable, and in the end the most expensive." 



Valuable as the above practical hints are, 

 some experience and judgment are needed be- 

 fore applying every one of them unreservedly to 

 circumstances in England. Reference has al- 

 ready been made (see pp. 79, 80) to the differing 

 thermometric readings in various machines, 

 which must be ascertained and allowed for ; and 

 it is manifest that keeping the temperature at 

 99° near the glass front, in vacant rows, while it 

 may be a good and sufficient rule for large 

 machines built on one general plan, and which 

 upon an average will have to " test out " a con- 

 siderable number of eggs, must be very uncertain, 

 and might be quite wrong, in other cases. It is 

 of course understood that 99° in such a vacant 

 position, in the coolest position near the glass 

 front, is equivalent to a proper heat over the 

 eggs farther back : but in a small SO-egg ma- 

 chine, with a spring batch of eggs all or nearly 

 all of which were strongly fertile, a thermometer 

 so placed might be nearly up to the egg-tem- 

 perature, and therefore too low. Intelligent 

 operators will, however, consider such points as 

 these, and notwithstanding find hints of value 

 from such a skilled exponent of American 

 practice. 



It should also be remarked that duck eggs 

 are, as a rule, longer hatching-out than hen egg.s. 

 The latter often come out six hours after pipping, 

 generally before twelve, and seldom later than 

 eighteen. Duck eggs are, in England, hardly 

 ever less than twelve, and often twenty-four, and 



