240 Mr. W. H. Barlow’s Account of Experiments 
examine and report on the state of the lighthouses. On my 
return I was requested to make a larger and more complete 
apparatus, in which I have succeeded to the full extent of my 
expectation. This last light burns for an hour; it is described 
below; but I must here first mention a circumstance attending 
our first exhibition. After this was over, Dr. Zohrab and my- 
self removed our apparatus, and there being still some gas 
in the bladders, we lighted it again for our own amusement 
in my drawing-office, when it exploded with great violence 
while I was pressing the bladders with my hands. You re- 
member the explosion of my gases in my little room at Rush- 
grove Cottage, but that was nothing; this was so sharp that 
T lost the sensibility of my right ear for nearly a month, and 
the explosion forced pieces of the bladders quite through the 
cloth of my trowsers; and yet, excepting my ear, I escaped 
without injury. 
In my large lamp it was necessary to have recourse to ga- 
someters instead of bladders. ‘These, according to Drum- 
mond’s description, were to act under a pressure of 30 inches 
of water; and ‘our explosion jhad taught us that this pres- 
sure must be very equable to prevent the mixing of the gases 
in any great quantity. Many were the schemes I had, and 
rejected, but at last I adopted the following :—A, fig. 2, is a 
cylinder of tin two feet in diameter, and four feet six inches 
high, closed at the bottom, and open at the top; B is another 
cylinder, one foot nine inches in diameter, of the same height, 
having a diaphragm at one foot eight inches from the bottom ; 
this formed the hydrogen gasometer, and was used as follows: 
From the bottom of the Jarger cylinder rose a pipe D, to the 
Fig. 2. 
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height of one foot nine inches, and a small recess was made 
