Reply to Mr. H. B. Leeson. 251 
Places. Dip. Intensity. 
are 6. gee BARS ae - 13482 
Cond Oity see's CU RERE POMS: OF) Wve, as 
Christiana ........ F230 i. od bE 124959 
Arendahl ........ Pe BGs ety el A756 
Brassa |. sitcenecs £2. 2) ey, eaowe 
Hare Island i33'5..54°82') 49 o..0.66. 16989 
Davis’s Straits..... 83 08 ........ 1°6900 
Baffin’s Bayete Jcseu 88 Dias iia 6685 
84 39 ........ 17349 
845 44 wei ccc d. 16943 
85. 592) eee 1°7383 
SOs OOU ae 3 ree 17606 
—o 
LV. Reply to Mr. H.B.Lerson. By J, Murray, F.L,S. 
M.W.S. &c. Ge. 
To Dr. Tilloch. 
Sir, — T nave 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 zron alone was proof against the action of quick- 
silver —Credat Judcus apella. 'The following are the words 
used by Mr. L. ina 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 Warinly recommend its use) the gaseous 
i2 mixture 
