Reply to Mr. H. B. Leeson. 251 
Places. - Dip. Intensity. 
FE cis oncnplewan a ae 2,9) 0. 6s ong eae 
BOAO, sso gone es ZOU aa fe 1°4142 
Christiana ........ 72 30 eoseecce 1°4959 
Arendahl. ..4.. see wo as covecres 1°4756 
Braise se cace! Pe ainiateipelts. JPA 
Hare Island ..3.... 82 49 eoccceee 1°6939 
Davis’s Straits ..... 83 08 sccocces 1°6900 
Baffin’s Bay....... 84 25 ........ 16685 
= Nas | Fe ane ig flop 
84 44 .,...... 1°6943 
85 592. ......6 17383 
ID oo ancewmee 7h F006 
Se 
LV. Reply to Mr. H.B. Lesson. By J. Murray, F.L.S. 
M.W.S, Se. Be. 
To Dr. Tilloch. 
Sir, — T save neither time nor inclination for any thing con- 
troversial, and least of all do I wish to disturb Mr, Leeson’s 
tranquillity, in reference to his « Safety Appendages” to Toft’s 
Hydrostatic Blowpipe. My remarks therefore on his last para- 
graph, which includes notice of me, shall be succinct. 
The use of mercury is conceded to me as recommended on the 
plan of Marquis Ridolfi; but it should seem either that I had 
omitted to state the necessity of a cell to contain it, or was ig- 
norant that iron alone was proof against the action of quick- 
silver —Credat Judeeus apella. 'The following are the words 
used by Mr. L. in a letter to me, dated 18th January last : ** You 
told me that mercury had been adopted (employed?) by the 
Marquis Ridolfi, and that you thought it preferable to oil or 
water ; on which I observed that the cylinder must in that case 
be made of iron!” 
When at Florence, this interesting young nobleman was good 
enough to sketch with his own hand, though labouring under a 
Severe accident, the consequence of chemical experiment, the 
attachment to the gas blowpipe, to which the preceding refers. 
You had the kindness to insert. in your pages a copy of this 
sketch and its description, Mr, Leeson might have there seen 
this described as of iron, 
Mr. Toft’s blowpipe was constructed at Nottingham, under 
Mr. Leeson’s directions; when finished, the instrument was 
charged with an explosive atmosphere, and at the orifice of Dr. 
Hope's Safety Box of Wire-gauze (certainly proof against all ex- 
plosion, nor can I too warily recommend its use) the gaseous 
112 mixture 
