MIC 



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MIL 



microscopes ever executed, of solid 

 substances, are those made of the 

 gems, such as garnet, ruby, dia- 

 mond, &c. Garnet is the best 

 material, as it has no double re- 

 fraction, and may be procured 

 perfectly pure and homogeneous. 

 When a single microscope is used 

 for opaque objects, the lens is 

 placed within a concave silver spec- 

 ulum, which concentrates parallel 

 or converging rays upon the face 

 of the object next the eye. 



When a microscope consists of 

 two or more lenses, or specula, one 

 of which forms an enlarged image 

 of objects, while the rest magnify 

 that image, it is called a compound 

 microscope. The ingenuity of phil- 

 osophers and of artists has been 

 nearly exhausted in devising the 

 best forms of object-glasses and of 

 eye-glasses for the compound mi- 

 croscope. Dr. Brewster. 



MICROSCO'PIC. That may be seen only 

 by the aid of a microscope. 



MICROSCO'PIC SHELLS. These are found 

 in prodigious abundance and of 

 such extreme minuteness, that in 

 their examination, and in the con- 

 sideration of them, our mental, 

 like our visual faculties, begin 

 rapidly to fail us when we attempt 

 to comprehend the infinity of little- 

 ness towards which we are thus 

 conducted. Of several species of 

 microscopic shells, five hundred 

 scarcely weigh a single grain, and 

 some are so exceedingly minute 

 that one thousand would scarcely 

 weigh a grain. In one ounce and 

 a half of stone from the hills of 

 Casciana, in Tuscany, Soldani ob- 

 tained 10,454 microscopic shells, 

 the remainder being principally 

 composed of comminuted fragments 

 of shells and spines of echini. 



MICROTHE'RIITM. The name assigned 

 to a fossil genus of small anoplo- 

 therioid herbivores. Entire crania 

 of the Microtherium, from the 

 lacustrine calcareous marls of the 



Puy- de-Dome are in the British 

 Museum. 



MI'EMITE. A mineral, thus named 

 from having been found at Miemo, 

 in Tuscany. A green variety of 

 Dolomite, occurring in crystals, 

 and in masses with a radiated 

 structure. 



MILK QUARTZ. The Milch Quartz of 

 Werner ; quartz hyalin laiteux of 

 Haiiy. A milk-white sub-species 

 of quartz, and distinguishable only 

 by its colour. It occurs massive. 

 Milk-quartz and rose-quartz are 

 considered by some mineralogists 

 as one and the same sub-species, 

 distinguished merely by their 

 colour, the one presenting a milky 

 appearance, while the other, 

 coloured by a minute quantity of 

 manganese, possesses a rose-red 

 colour, sometimes passing into a 

 flesh-red or crimson-red. 

 MI'LLEPEDE. } (millepeda, Lat. from 

 MILLIPEDE. ) miHe t a thousand, and 

 pes, a foot.) Insects whose body 

 is generally cylindrical ; segments 

 half membraneous and half crusta- 

 ceous, each half bearing a pair of 

 legs; antenna3 seven-jointed, fili- 

 form, often a little thicker towards 

 the end. These are called milli- 

 pedes. The millipedes belong to the 

 necrophagous tribe, or those which 

 devour dead animals, or any 

 other putrescent substances. 

 jffirby. 



MILLE'PORA.. | (from mills, a thousand, 

 MI'LLEPORE. ) and porus, a pore.) 

 A genus oflithophytes or zoophytes 

 of various forms, having the surface 

 perforated with numerous small 

 pores or holes. A stony, internally 

 solid, polymorphous, ramose or 

 frondescent polypifer, pierced by 

 simple, not lamellated pores. The 

 pores cylindrical, and perpendicular 

 to the axis, or to the expansions of 

 the polypifer; for the most part 

 small, and sometimes not apparent. 

 Parkinson. In millepores the 

 cells are more minute and close 



