Everything in chemistry often comes with a strong reason and facts behind it, but I stuck in definition of $1$ calorie.
My reference book define one calorie as amount of heat required to raise the temperature of one gram of water from $14.5$ degrees Celsius to $15.5$ degrees Celsius.
Why $14.5$ and $15.5$, why temperature such as $0$ to $1$ or $19$ to $20$ degree Celsius is not chosen?
Please forgive me if this question is too easy and I can't figure out the logic related to it.
I shall be glad to have your suggestions.