^oo Sir Benjamin Thompson’s 
The refult of thefe experiments, I confefs, furprifed me 
not a little ; but the difcovery of truth being the foie object of 
my inquiries (having no favourite theory to defend) it brings 
no difappointment along with it, under whatever unexpected 
fhape it may appear. I hope that further experiments may lead 
to the difcovery of the caufe why there is fo little difference in 
the conducting powers of air of fuch very different degrees of 
rarity, while there is fo great a difference in the conducting 
powers of air, and of the Torricellian vacuum. At prefent, 
I fhall not venture any conjectures upon the fubject ; but in the 
mean time I dare to affert, that the experiments 1 have made 
may be depended on. 
The time of my flay at Manheim being expired (having had 
the honour to attend thither his moft Serene Highnefs the 
Elector Palatine Duke of Bavaria, my moft Gracious Mafter, 
in his late journey), I was prevented from purfuing thefe in- 
quiries further at that time ; but I fhall not fail to recommence 
them the firft leifure time I can find, which I fancy will be 
about the beginning of the month of November. In the mean 
time, to enable myfelf to purfue them with effect, I am 
fparing neither labour nor expence to provide a complete appa- 
ratus neceflary for my purpofe ; and his Electoral Highnefs 
has been gracioufly pleafed to order M. Artaria (who is in 
his fervice) to come to Munich to affift me. With fuch a 
Patron as his moft Serene Highnefs, and with fuch an affiftant 
as Artaria, I fhall go on in my purfuits with chearfulnefs. 
Would to God that my labours might be as ufeful to others as 
they will be pleafant to me ! 
I fhall conclude this letter with a fhort account of fbme 
experiments I have made to determine the conducting powers 
4 of 
