I have my fist new lot of eggs at 18 days since the second egg was laid, so I'm beginning to have my serious doubts. Its a bit cold here at present so they could have gotten a chill on the eggs or as discussed below, due to the low humidity at the moment the egg shells may have been a bit hard to hatch?? I thought I'd share this extract from "The Bengalese Finch"pg. 26
The incubation period is between twelve, and fourteen days, depending on when the pair started to sit properly. A good guide is to count seventeen days from the first egg laid, that will give you hatching date give or take a day.
A few days before the eggs are due to hatch you should provide a constant supply of bath water, so the sitting pair can maintain the correct humidity in the nest box. If the nest is too dry the chicks may have difficulty in breaking out of the shell, resulting in "dead in shell" the poor baby has exhausted its self and died trying to break out of the shell. Poor ventilation, and dry humidity, can be the cause of chicks being unable to break out of the shell, therefore resulting in dead in shell. As we have already said giving the birds a bath every day can help to offset this particular problem.
