I have hatched and raised birds successfully many times before. Try to keep the temp up a little more.. if it's a still-air, i suggest 104, if it has a fan than push it up to 100. birds are warmer than chickens. and BTW, those are sparrow eggs. Once they hatch, they need to be fed tiny TINY bits of high quality cat food soaked in warm water (MUST be fresh made every 4 hours) with a toothpick on the right side of their throat every 20-30 minutes for 2 days. then make it every 45 minutes until their eyes open, than you can make it every hour. you need to keep it in the incubator until it gets its mini little feathers (a few days) than you can move it to some other kind of brooder around 85-90 degrees F. and once it gets old enough, you have to go outside with it daily to teach it how to fly, then teach it how to find bugs, then teach it how to avoid predators, then teach it how to sing, call, etc. it's extremely hard and basically no body can do it. No, birds do not have 'natural instincts' . their parents do everything for them, and then teach them how to fly. then they stay with their parents until summer is over. in that time period, they learn how to be a bird.
If you raise it yourself, you will most likely fail at it, and if you succeed it will probably be lonely, loud, not cared enough for, and un-able to be released.
I highly suggest hatching it, and once it is hatched, take it RIGHT AWAY to a wildlife shelter. Since it needs to be fed in 15-30 minutes within hatching, you need to take it to the wildlife care center the moment it happens. not kidding. and it needs to be kept warm in the car, which is extremely hard.
Wild birds aren't chickens. they aren't parakeets, either. and the wildlife center won't take the time to hatch it, so that's up to you. and once it is out of its little shell, rush that sweetheart to a shelter immediately.
Also, it's illegal to keep wild birds. so please. don't raise it yourself. It's a living creature just like you and me. It deserves to be in the best hands we can give it, and needs to live the life a bird was meant to have. this is only possible if you bring it to the wildlife care shelter.