4162 MACHINE ror MEASURING a 
prefented in Fig. 2. The rod muft havea fhoulder to bear 
‘on the upper edge of the focket, to prevent its flipping 
quite down. The rod mutt alfo pafs through a like focket 
at F, Fig. 1. The joint of the lower focket muft be fixed 
to the bow of the fhip, and the upper joint or focket muft 
‘be conneéted with the horizontal arm E. On the top of 
the uppermoft focket, let there be a fmall circular plate, 
bearing the 32 points of the mariner’s compafs ; and let 
the top of the rod AB come through the centre of this 
plate, fo as tocarry a {mall index upon it, as is reprefent- 
ed in Fig. 3. This fmall index muft be fixed to the top 
of the rod on a fquare ; fo, that by turning the index round 
the plate, the rod may alfo turnin the fockets, and of courfe 
carry the palate Dround with it. The little index always 
pointing in a direction with the face of the palate. The 
{mall compafs plate fhould not be faftened to the top of 
the focket, but only fitted tightly on, that it may be move- 
able at pleafure. Suppofe, then, the intended port to bear 
fouth-weft from the place of departure ; the palate muft be 
turned on the focket till the fouth-weft point thereon looks 
dire@tly to the fhip’s bow; fo that the fouth-weft and 
north-eaft line on the compafs plate may be precifely pa- 
rallel with the fhip’s keel; and in this pofition the plate 
muft remain during the whole voyage. Suppofe then the 
fhip to be failing in the dire& courfe of her intended voy- 
age, with her bow{prit pointing fouth-weft, let the little 
index be brought to the fouth-weft point on the compafs 
plate, and the palate D will neceflarily prefent its broad 
face toward the port of deftination; and this it muft al- 
ways be made to do, be the fhip’s failing courfe what it 
may. If, on account of unfavourable winds, the fhip is 
obliged to deviate from her intended courfe, the little in- 
dex muft be moved fo many points from the fouth-weft 
line of the compafs plate, as the compafs in the binnacle 
fhall fhew that fhe deviates from her true courfe. So that, 
in whatever dire€tion the fhip fhall fail, the palate D will 
always 
