MAD 



swimming on the surface, which are gene- 

 ral ed and dissolved by causes little known 

 to us : but whatever these solar spots 

 are, it is certain they are produced from 

 causes very inconstant and irregular ; for 

 Scheiner says he frequently su\v fifty at 

 once, but for twenty years after scarce 

 any appeared. And in the last century 

 the spots were very frequent and nume- 

 rous till the year 1741, when, for three 

 years successively, very few appeared; 

 and now, since the year 1744, they have 

 again appeared as usual. 



These macula are not peculiar to the 

 sun, they have been observed in all the 

 planets. Thus Venus was observed to 

 have several by Signior Blanchini, in the 

 year 1726. As in Venus, so in Mars, 

 both dark and bright spots have been ob- 

 served, first by Galileo, and afterwards by 

 Cassini, &c. Jupiter has had his spots 

 observable ever since the invention and 

 use of large telescopes. Saturn, by reason 

 of his great distance on one hand, and 

 Mercury, by reason of his smallness and 

 vicinity to the sun on the other, have not 

 as yet had any spots discovered on their 

 surfaces, and consequently nothing in re- 

 lation to their diurnal motions and incli- 

 nations of their axis to the planes of their 

 orbits can be known, which circumstances 

 are determined in all the other planets, 

 as well as in the sun, by means of these 

 maculae. 



The spots, or macube, observable on the 

 moon's surface, seem to be only cavities 

 or large caverns, on which the sun shin- 

 ing very obliquely, and touching only 

 their upper edge with his light, the 

 deeper places remain without light ; but 

 as the sun rises higher upon them, they 

 receive more light, and the shadow, or 

 dark parts, grow smaller and shorter, till 

 the sun comes at last to shine directly 

 upon them, and then the whole cavity 

 will be illustrated : but the dark dusky 

 spots, which continue always the same, 

 are supposed to proceed from a kind of 

 matter or soil which reflects less light 

 than that of the other regions. See 

 Moosr. 



MADDER is a plant, with rough nar- 

 row leaves, set in form of a star, at the 

 joints of the stalk. The root, which is 

 the only part made use of, is long, slender, 

 of a red colour, both on the outside and 

 within, excepting a whitish pith which 

 runs along the middle. For cultivating 

 this plant, the ground is ploughed deep 

 in autumn, and again in March ; and then 

 laid up in ridges, eighteen inches asunder, 

 and about a foot high. About the begin- 

 ning of April, they open the ground 



where old roots are planted, and take off 

 all the side shoots which extend them- 

 selves horizontally ; these they transplant 

 immediately upon the new ridges, at 

 about a foot distance, where they remain 

 two seasons: and at Michaelmas, when 

 the tops of the plants are decayed, they 

 take up the roots. It is to be observed, 

 that this method of planting in ridges is 

 only necessary in wet land, and that the 

 rows are sometimes planted three feet, 

 and the plants in the rows eighteen 

 inches asunder. If all the horizontal 

 roots are destroyed from time to time, it 

 will cause the large, downright roots, to 

 be much bigger, in which the goodness 

 of this commodity chiefly consists. Mad- 

 der gives out its colour, both to water and 

 rectified spirit : the watery tincture is of 

 a dark dull red ; the spirituous of a deep 

 bright one. It imparts to woollen cloth, 

 prepared with alum and tartar, a very 

 durable, though not a very beautiful red 

 dye. As it is the cheapest of all the red 

 drugs that give a durable colour, it is the 

 principal one commonly made use of for 

 ordinary stuffs. Sometimes its dye is 

 heightened by the addition of Brazil- 

 wood, and sometimes it is employed in 

 conjunction with the dearer reds, as 

 cochineal; for demi-scarlets, and demi- 

 crimsons. 



MADREPORA, in natural history, a 

 genus of the Vermes Zoophyta class and 

 order. Animal resembling a medusa; 

 coral with lamellate star-shaped cavities. 

 This is a very numerous genus, compre- 

 hending about 120 species, separated into 

 distinct divisions. A. composed of a sin- 

 gle star. B. with numerous separate 

 stars, and continued gills. C. with nume- 

 rous united stars. D. aggregate, undivid- 

 ed, with distinct stars and porulous tuber- 

 culous prominent undulations. E. branch- 

 ed, with distinct stars and tuberculous 

 porulous undulations. M. verrucaria, 

 star orbicular, flattish, sessile, with a con- 

 vex disc full of tubular pores and radiate 

 border : it inhabits the European, Medi- 

 terranean, and Red Seas, adhering to ma- 

 rine vegetables and the softer zoophytes; 

 size of a split-pea, and appears an inter- 

 mediate species between the madrepore, 

 tubipore r and millepore ; white or yel- 

 lowish, with aggregate tubes on the disc 

 like the florets of a composite flower, and 

 a flattened striate border like the rays of 

 these flowers. A. ananas, with angular 

 convex stars, which are concave on the 

 disc, inhabits the Mediterranean and 

 South American Sea, and is frequently 

 found fossile ; gibbous, and when dis- 

 sected transversely, resembling a white 



