XX.IV 
OFFICIAL INSTRUCTIONS. 
vessels placed under your orders to separate, except in the event 
of accident or unavoidable necessity, and we desire you to keep 
up the most unreserved communications with the commander of 
the Griper; placing in him every proper confidence, and ac- 
quainting him with the general tenor of your orders, and with 
your views and intentions, from time to time, in the execution 
of them; that the service may have the full benefit of your 
united efforts in the prosecution of such a service; and that, 
in the event of unavoidable separation, or of any accident to 
yourself. Lieutenant Liddon may have the advantage of knowing, 
up to the latest practicable period, all your ideas and inten- 
tions, relative to a satisfactory completion of this interesting under- 
taking. 
We also recommend, that as frequent an exchange take place, 
as conveniently may be, of the observations made in the two 
ships ; that any scientific discovery made by the one be, as 
quickly as possible, communicated for the advantage and guidance 
of the’ other, in making their future observations ; and to increase 
the chance of the observations of both being preserved. 
We have caused a great variety of valuable instruments to be put 
on board the ships under your orders ; of which you will be furnished 
with a list, and for the return of which you will be held responsible ; 
and we have also, at the recommendation of the President and Council 
of the Royal Society, ordered to be received on board the Hecla, 
Captain Sabine, of the Royal Artillery, who is represented to us as 
a gentleman well skilled in Astronomy, Natural History, and various 
branches of knowledge, to assist you in making such observations as 
may tend to the improvement of Geography and Navigation, and the 
