[62] PAGE 13, LINE 4. Page 13, line 3. [Greek: mikrogê] _seu Terrella_. Although rounded loadstones had been used before Gilbert's time (see Peregrinus, p. 3 of Augsburg edition of 1558, or Baptista Porta, p. 194, of English edition of 1658), Gilbert's use of the spherical loadstone as a model of the globe of the earth is distinctive. The name _Terrella_ remained in the language. In _Pepys's Diary_ we read how on October 2, 1663, he "received a letter from Mr. Barlow with a terella." John Evelyn, in his _Diary_, July, 1655, mentions a "pretty terella with the circles and showing the magnetic deviations."
A Terrella, 4½ inches in diameter, was presented in 1662 by King Charles I. to the Royal Society, and is still in its possession. It was examined in 1687 (see _Phil. Transactions_ for that year) by the Society to see whether the positions of its poles had changed.
In Grew's _Catalogue and Description of the Rarities belonging to the Royal Society and preserved at Gresham College_ (London, 1681, p. 364) is mentioned a Terrella contrived by Sir Christopher Wren, with one half immersed in the centre of a plane horizontal table, so as to be like a Globe with the poles in the horizon, having thirty-two magnet needles mounted in the margin of the table to show "the different respect of the _Needle_ to the several _Points_ of the _Loadstone_."
In Sir John Pettus's _Fleta Minor_, London, 1683, in the _Dictionary of Metallick Words_ at the end, under the word _Loadstone_ occurs the following passage:
"Another piece of Curiosity I saw in the Hands of Sir _William Persal_ (since Deceased also) _viz._, a _Terrella_ or _Load-stone_, of little more than _6 Inches Diameter_, turned into a _Globular Form_, and all the _Imaginery Lines_ of our _Terrestrial Globe_, exactly drawn upon it: _viz._ the _Artick _ and _Antartick Circles_, the _two Tropicks_, the _two Colures_, the _Zodiack_ and _Meridian_; and these _Lines_, and the several _Countryes_, artificially _Painted_ on it, and all of them with their true _Distances_, from the two _Polar Points_, and to find the truth of those _Points_, he took two _little pieces_ of a _Needle_, each of about _half_ { 24} _an Inch in length_, and those he laid on the _Meridian line_, and then with _Brass Compasses_, moved one of them towards the _Artick_, which as it was moved, still raised it self at one end higher and higher, keeping the other end fixt to the _Terrella_; and when it had compleated it Journy to the very _Artick Points_, it stood upright upon that _Point_; then he moved the other piece of _Needle_ to the _Antartick Point_, which had its _Elevations_ like the other, and when it came to the _Point_, it fixt it self upon that _Point_, and stood _upright_, and then taking the _Terrella_ in my Hand, I could perfectly see that the two _pieces_ of _Needles_ stood so exactly one against the other, as if it had been one intire _long Needle_ put through the _Terrella_, which made me give credit to those who held, That there is an _Astral Influence_ that _darts_ it self through the _Globe_ of _Earth_ from _North_ to _South_ (and is as the _Axel-Tree_ to the _Wheel_, and so called the _Axis_ of the _World_) about which the _Globe_ of the _Earth_ is turned, by an _Astral Power_, so as what I thought _imaginary_, by this _Demonstration_, I found _real_."