Hayden — Oil Respiration of Coni2)ressed Air. 203 
within the drums has a tendency to open the tubes, and thus facilitates 
its escape through them ; whereas increasing the pressure has the 
effect of collapsing them, and therefore it makes it more difficult to 
admit the compressed air within the cavities of the ears. It frequently 
occurs, however, from some abnormal condition of these tubes, as 
when influenced by a cold in the head, that neither of these remedies 
will relieve the pain. 
To continue the admission of compressed air into the lock, under 
these circumstances, would intensify the suffering, and possibly rup- 
ture the tympanum : therefore the lock tenders were particularly in- 
structed to shut off the compressed air at the moment any one in the 
lock experienced pain about the ears ; and then, if it could not be 
relieved by the above means, the lock was opened, and the person was 
not permitted to go through into the air-chamber. Sometimes fifteen 
minutes were occupied in passing persons through the first time, after 
which they usually had no further trouble from this cause. 
The fact that the depth penetrated by the air-chamber was con- 
siderably greater than that hitherto reached in any similar work, left 
me without any benefit from the experience of others in either guard- 
ing against any injurious effects of this great pressure upon the work- 
men and engineers subjected to it, or of availing myself of any known 
specific for relieving those affected by it. When the depth of sixty 
feet had been attained, some few of the workmen were affected by a 
muscular paralysis of the lower limbs. 
This was rarely accompanied with pain, and usually passed off in 
the course of a day or two. As the penetration of the pier progressed, 
the paralysis became more difficult to subdue. In some cases the arms 
were involved, and in a few cases the sphincter muscles and bowels. 
The patients also suffered much pain in the joints when the symptoms 
were severe. An average of at least nine out of ten of those affected 
suffered no pain whatever, but soon recovered, and generally returned 
to the work. 
"The duration of the watches in the air- chamber was gradually 
shortened from four hours to three, and then to two, and finally to one 
hour. 
' ' The use of galvanic bands or armour seemed, in the opinion of 
the superintendent of construction, the foreman of the chamber, and 
the men, to give remarkable immunity from the attacks. They were 
all ultimately provided with them. These bands were made of alter- 
nate scales of zinc and silver, and were worn around the wrists, arms, 
ankles, and waist, and also under the soles of the feet. Sufficient 
moisture and acidity were supplied by the perspiration to establish 
galvanic action in the armour, and as the opinion amongst those most 
accustomed to the chamber was almost unanimous in favour of this re- 
medy, I am very much inclined to believe it valuable. 
* ' The total number of men employed in the air chamber of this 
pier was 352. Of this number about thirty were seriously affected. 
Notwithstanding the care and skill with which those most severely 
