193 ALONG THE FLORIDA REEF. 



boat was steadied they dived down. When the 

 water had cleared, the lookers-on saw them swim 

 rapidly to the dark object. Then they evidently 

 touched it, as a cloud of mud or sand almost ob- 

 scured them from view. Hardly half a minute 

 elapsed before they both appeared and were at 

 the surface, hanging to the boat, puffing and 

 blowing. 



" It's an old cannon," said Tom breathlessly ; 

 "I've discovered something piratical this time 

 surely." 



" Where do you suppose it came from ? " 

 asked Harry of the doctor. 



" It may have been from one of the old pi- 

 rates," he replied. 



" It is covered with weed and coral," con- 

 tinued Tom ; " but if that was scraped off we 

 might find a mark on it. Here goes ! " and he 

 again sank beneath the surface, followed quickly 

 by his companion. 



This time they dug the sand away from the 

 gun, and when again at the boat the hole they 

 had made by its side exposed the cannon to full 

 view. 



