The Davy. 143 
stroyed as soon as the work is printed, many who may wish at- 
‘terwards to possess a copy, and to whom it might prove highly 
serviceable, must be disappointed. 
New Variation Chart.—All the variation charts hitherto pub- 
lished, have been only transcripts of Dr. Halley’s original chart, 
with few corrections for the change of variation since his time, 
and none of them extending beyond the Atlantic and Indian 
Oceans. Navigiators have therefore long regretted the want of an 
accurate variation chart, comprehending the whole circuit of the 
navigable ocean and seas of our globe. To supply this want, 
Mr. Thomas Yeates has, with much labour and care, constructed 
@ variation chart of all the navigable oceans and seas between 
latitude 60° north and south, from accurate documents obtained 
of Spanish surveys in the Pacific Ocean; journals at the Hydro- 
graphical Office, Admiralty; and at the East India House; col- 
Jated with tables of the variation recently formed from the ob- 
‘servations of different navigators. This chart is delineated on 
“a new plan, all the magnetic meridians being’ drawn upon it 
throughout, for every change of one degree in the variation; and 
it will be elucidated with explanatory notes, and a brief state- 
ment of the late discovery of an aberration in the variation, re- 
sulting from the deviation or change of a ship’s head from the 
‘magnetic meridian, accompanied by the rules invented by the 
late Captain Flinders for correcting the same. It is to be pub- 
lished by subscription (price half-a-guinea) at Messrs. Black, 
Parbury, and Allen’s, No. 7, Leadenhall-street; Mr. E. Trough- 
ton’s, No. 136, Fleet-street; and Mr. Bates’s, Poultry. 
XXIII. Intelligence and Miscelianeous Articles. 
To Mr. Tilloch. 
Sin, — I BEG to add something explanatory relative to an ex- 
pression of mine in the communication you were pleased to in- 
sert in your last Number, I said that the safety promised by 
‘the * Davy’ was questioned by those “ who ought to have known 
better.” Certainly there never was any thing more unphiloso- 
phical than the opposition it met with from them, and this even 
continued after it had been proved secure in the mine itself. 
Some raised their voice against it who never saw it, and had only 
heard of it through the medium of imperfect description. Others 
had seen it, but such had never made the experiment, and they 
yet rudely questioned its efficiency. Others still more daring, 
subjected it to experiments totally unconnected with the phe- 
homena of the mine; and, determined to pervert its value, So 
a false 
