In the Galileo Museum in Florence there is a terrella twenty-seven inches in diameter, of loadstone from Elba, constructed for Cosmo de' Medici.
It is not clear, at this point, whether he believed a "properly balanced" terrella would be a perpetuum mobile.
In spite of the weaknesses of the method of analogy, Gilbert's experimental model of the terrella to interpret the earth's magnetism was as much a contribution to scientific method as to the theory of magnetism.
The method of analogy was used again in his comparison of the properties of a magnetized needle placed over a terrella with the properties of a compass placed over the earth, whence he concluded the earth to be a giant loadstone.
In developing his theory of terrestrial magnetism, Gilbert fell into certain errors, chiefly for want of data, but partly also by reason of his adherence to the view that the earth exactly resembled his terrella in its magnetic action.
A Loadstone attracts magneticks not only to a fixed point or pole, but to every part of a terrella save the aequinoctial zone.
At very short distances close to the terrella the moving impetus is greatest.
The centre C is placed on the surface of the larger terrella, because the smallerterrella shows some variation on account of the length of the axis; inappreciable, however, on the earth.
These facts have been pointed out to me and confirmed by our most illustrious Sea-god, Francis Drake, and by another circumnavigator of the globe, Thomas Candish; our terrella also indicates the same thing.
If a spike is set up on the pole of a loadstone, a spike or style * of iron placed on the upper end is strongly cemented to it, and draws away the erect spike from the terrella when motion is made.
Just so magneticks or iron bodies on the surface of a terrella ought not to have too long an axis, but a very short one; so that they may make a declination on the terrella truly and naturally proportionate to that on the earth.
Nor do these also exist on the earth or on a terrella for the sake of the turning merely; but they are also limits of direction and position, both as respects destined districts of the world, and also for correct turnings among themselves.
There is set up above the Northern pole of the smaller terrella a spike larger than the pole b of the smaller terrella can raise, if it is turned round to the higher parts.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "terrella" in a variety of sentences. We hope that you will now be able to make sentences using this word.
