59 
Mr Adie on the Sympiesometer, 
continued to the latitude of 76^" 50' N. and during the return of 
the Expedition to Deptford till the 13th of November. These 
observations, in the form of a graphical representation of the 
progress of the Sympiesometer and Marine Barometer, have 
been published in Captain Ross’s Account of the Expedition, 
and will enable navigators to form a correct estimate of the re- 
lative value of the two instruments 
The following is Captain Ross’s official report upon the Sym- 
piesometer : 
This instrument acts as a marine barometer, and is certain- 
ly not inferior in its powers. It has also the advantages of not 
being affected by the ship’s motion, and of taking up very little 
room in the cabin. I am of opinion that the instrument will 
supersede the Marine Barometer, when it is better known.” 
Lieutenant Robertson, in a letter to the Honourable Cap- 
tain Napier of Merchistoun, has spoken of it in the following' 
manner : 
The Sympiesometer is a most excellent instrument, and 
shews the weather far better than the Marine Barometer. In 
short, the barometer is of no use compared to it. If it has any 
fault, it is that of being too sensible of small changes, which 
might frighten a reef in when there was no occasion for it ; but, 
take it altogether, in my opinion it surpasses the mercurial ba- 
rometer as much as the barometer is superior to having ijone at 
all.” 
I have also had it in my power to make trial of the Sympie- 
someter on coasting voyages, through the favour of my friend 
Mr Stevenson, Engineer to the Scots Lighthouse Board, who 
placed one of them in the cabin of the Lighthouse Yacht beside 
a good marine barometer. Along with a register of both instru- 
• We have now before us a copy of these observations, both in a tabular and 
projected form. The superior delicacy of the Sympiesometer is very remark- 
able. It frequently exhibited vaiiations in the pressure of the atmosphere 
when the Marine Barometer was perfectly stationary, and thus predicted 
changes in the weather, when the other instrument gave no indications at 
all. We have likewise seen the observations made with the Sympiesometer by 
Captain Bailing, of his Majesty’s ship Nimrod, who has expressed the highest 
opinion of the superiority of the Sympiesometer. On one occasion in particular, 
it enabled him to make successful preparations against a storm, which was not 
xn4icated by the Marine Barometer. Ea, 
