expended in swimming to the bottom, where they can remain only a very few seconds, as time must be allowed for reaching the surface before letting go their breath. Practice in ever-varying depths enables them to gauge this limit of time to a nicety. But sometimes they cut things too fine, and then a catastrophe was inevitable, unless much watchfulness was exercised by the white man, who has to keep his eyes turned in all directions once his men are down. So long as a diver can hold his breath the pressure forces him to the surface at a speed which seldom requires accelerating by strokes with the hands or feet; but the moment he lets go his breath—if under water—his upward course is arrested and his body commences to sink. Now, when the white man sees this, either he must plunge in to the rescue himself, or direct such divers who may be on the top to do the needful. On a calm day, when one can see far into the blue clear depths below, I have often seen one of my men shooting rapidly upwards until within perhaps a foot or two from the surface, when a sudden gush of bubbles from the man’s mouth would tell its own tale. Instantly he would begin to sink gently downwards, and only quick action could save this diver who had miscalculated his time. However, as it was not infrequent for divers to go down and never come up at all, one may conclude that, where the time to be allowed is comprised in so few seconds, even the most experienced make fatal errors.[251] The difficulties in securing labor at length resulted in experiments with the scaphander or diving dress, and gradually its adoption by most of the pearling fleet. The labor problem and the exhaustion of the oysters in medium depths developed more quickly in Torres Straits than on the northwest coast, and diving outfits were introduced there about 1879, while this was delayed about five years longer on the northwest coast. The outfit did not immediately supplant nude diving in either locality. In 1883, only 80 of the 206 Queensland vessels were supplied with scaphanders, the others continuing to use nude diving, and even yet nearly one third of the vessels depend on that form of fishery. Of the 353 vessels fishing in 1904, 108 depended on nude divers and 245 were supplied with armored equipment.