How do I know my eggs in the incubator are good?

[natyvidal]

Hi everyone! I have a clutch of eggs in the incubator since last Saturday. So today it is a week.
I want to kindle them to find out if they are good or bad. The hens might not have been keeping them warm during the nights and the temperatures were down to the mid 40's. So What am I supposed to be looking for? Thank you. Merry Christmas.

 

[igorsMistress]

What kind of eggs? You should see veins when you candle.

 

[BirdsBeesTrees]

https://www.backyardchickens.com/threads/egg-candling-tips-tricks-and-best-practices.1462841/