"[Y]ou desire me to give you... my thoughts upon the Construction and Use of Chimneys... I embrace willingly this leisure... to comply... as it will not only fhew my regard to... a friend, but may... be of some utility to others; the doctrine of chimneys appearing not to be as yet generally well understood, and mistakes respecting them being attended with constant inconvenience, if not remedied; and with fruitless expence, if the true remedies are mistaken."