252 Reply to Mr. H. B. Leeson. 
mixture burnt tranquilly. It was unscrewed, and the gas ignited 
at the extremity of a capillary tube; the flame receded, an ex- 
plosion ensued, and the instrument was destroyed. Mr, Lee- 
son’s *¢ valve therein” was @ common button valve. This is the 
circumstance which Mr. L. would inform us of at page 403 of 
your December Number, ; 
Having said thus much for the safety cistern, I shall now ad- 
vert to the “ valve therein.” 
From the explosion adverted to, which Mr. L. ascribed to the 
valve being rudely made, I concluded that some other plan of 
the valve was advisable, though Mr. Leeson thought the same 
valve repaired would do. The plan I proposed is now intro- 
duced in Mr. Leeson’s own words, quoted also from his letter of 
18th January. It was submitted before Mr. L. to one Andayna 
for such alteration and improvement as he saw necessary. 
** Your plan of two button valves, to be connected 
together by a solid spindle up the sides of which the 
gas was to pass, and which were to be rendered air- 
tight by two pieces of leather attached to their under 
surfaces, and the buttons were to be prevented from 
rising too high by two small bits of wire inserted above 
the upper valve.” This may perchance be pronounced 
not a ** modification”? of that to which we find 
** H. B. Leeson invt, et del.” attached. But thereis [=] 
no doubt of its being equally safe—by this provision a 
of a double’ guard both valves closing simultaneously. i: 
Allow me to ask, sir, why this anxiety to entertain us with 
different arrangements of the “ Safety cistern and valve therein?” 
The bundle of wires deposited in the cell serves all the purposes 
of the wire-gauze with which Mr. L. mow crams the cistern; and 
under such circumstances, which is merely placing Dr. Hope’s 
wire-gauze box within the cistern, instead of exterior to it, the 
instrument would be safe without any valve at all; aye, or even 
mercury. 
I own that T was much amused with * experiment” and “ ex 
plosion,” nay, “repetitions” of them, so loudly vaunted in 
Mr. Leeson’s ** new observations ;”” being sadly sceptical, whether 
coming from this young gentleman, I am to regard them vor 
et preterea nihil. Mr, Leeson in aletter to me (138th Novem- 
ber) advised “a good way of trying the Safety Appendages,” 
-——“ to connect them with a bladder containing the explosive 
mixture, set a candle before the jet and open the cock of the 
jet-pipe by a long string!’’ Are we to understand that his 
*“ experiments,” ‘¢ explosions,” and ‘‘ repetitions,’’ were made 
in this manner ? 
I honestly confess that I am sorry for having written the note 
annexed 
