Identify the poisoned bottle....
A king plans for a feast, one month before the feast 1000 barrels of wine arrive as per the king's order, but a spy poisons one of the bottles and escapes before being caught.
Now the king have 10 servants at his disposal, he needs all the remaining 999 bottles for the feast.
The poison is deadly and even the slightest amount of it can is fatal, it takes 3 weeks for the poison to work.
How can the king identify which bottle was poisoned?