« 
of measuring Time at Sea. 138 
into the tecth of the balance wheel, and then several teeth 
escape. Lastly, after many attempts of this kind, I was 
only completely satisfied with that of the new marine watch. 
: Article VI. 
Of the compensation for the effects of heat and cold :—Of 
the necessity of preserving to the spiral spring an inva- 
riable length:— Means by which, without changing this 
fength, we regulate the new watch to almost the smallest 
quantity :—Description ef the new compensation, Sc. 
The first thing that I thought necessary to clear up before 
_ Tattempted to compensate the effects of the different de- 
grees of heat and cold in my machine, was, the proportion 
that its gain or joss followed by these different degrees. I 
feared much that this progression was not proportional te 
that of the degrees marked by the thermometer; that, for 
example, the watch having lost three seconds for six degrees 
of ascent in the thermometer, it would not lose six for 
twelve degrees of this same instrument, but either a greater 
or less quantity. Various. reiterated experiments happily 
proved to me that my fears were unfounded; that when the 
regulator was free, as it is in my machine, the progression 
of gain or loss absolutely follows that of the thermometer ; 
that is to say, that the watch losing 3 seconds when the 
thermometer from 0 passes to 6, it will lose 6 at 12, 9 at 
i8, and so on. IE in our researches nature often contradicts 
our views, we may say that she is sometimes more favour- 
able than we had reason to hope: of this, the precision to 
which clock-work is arrived furnishes undoubted proofs. 
All this shows the indispensable necessity of having a 
perfectly free regulator, without which, the effect of heat on 
the machine depending more or less on the fluidity of the 
oii, which is very variable in different degrees of heat and 
cold, and the alterations of this fluidity, produced by time 
and by the wear of the parts, &c., the progression remarked 
above no longer takes place, and bas not even any thing 
certain: this is a just objection made by M.'Basser* against 
Mr. Harrison, among a number of others which are not so, 
* See the Gazette du Commerce. 
13 After 
