492 Portable Machine for loading and unloading Goods. 
at reft in, the common interfeétion of the lines of the magneti¢ 
meridian or variation and dip; nor can any alteration of di- 
retion or motion of the fhip affect a dipping needle thus 
fufpended._ 
In confequence of this fimple contrivance, the motion or 
gyration of the graduated circles for either dip of variation on 
account of the motion of the fhip, becomes totally avoided ; 
for, on or in thefe magnetic inftruments there are no divi- 
fions whatever: the inftruments themfelves can be afforded 
for half the price of others; the navigator makes his obferv- 
ations like a man of fcience; and finally, he determines with 
expedition, eafe, and certainty, the magnetic dip and varia~ 
tion, to degrees, minutes, and feconds, 2. ¢. to the like ac- 
curacy that he can diftinguifh or read the fubdivifions fhewn 
by the vernier on the arch of his fextant: a circumftance ut- 
terly impoffible to be obtained even to whole degrees, it might 
be faid to half a dozen degrees, by any other conftruéted in- 
ftruments, as has'been herein before fufficiently verified. 
XII. Defeription of a Portable Machine for loading and un- 
loading Goods. By Mr, Gzorcer Davis, of Windfor, 
Berks *. ; 
Lu E ingenious contriver of this machine is certain, that, 
when made of its intended fize, it will be capable of loading 
a ton weight by one man only, and will be fo portable as not 
to exceed one hundred and twelve pounds in weight. 
Reference to the Figure of the Machine. (See Plate IX.) 
A, the winch, which turns the bar B. This bar has on 
it two, endlefs {crews or worms C,C, which work in the 
toothed wheels D, D. Thefe wheels are fixed fo the barrels 
E,E, round which the ropes F, F, coil, wind up, or let out 
the fame occafionally ; which ropes, pafling over the two 
* From the Tranfadtions of the ail Sor the Encouragement of Arts, 
Manufactures, and Commerce, 
A premium of fgrty guineas was given to Mr. Davis for this invention. 
pulleys 
