How were the four boys rewarded at end of the day in the classic The Swiss Family Robinson

From the text:

We had two days of incessant labour in fitting and loading the pinnace; finally, after putting up our masts, ropes, and sails, we selected a cargo of things our boats could not bring. When all was ready, my boys obtained permission, as a reward for their industry, to salute their mamma, as we entered the bay, by firing our two guns.