RECHKATIVK B< 



311 



Ancimt and viodtr* pkao-<ojJr. 

 re and M0d ttortei. 



Lot philosophy aucion* et lot 

 et lo second <taB. 



NOTE. In this case the noun expressed u used in the 



ainguliir. 



i, however, the two adjectives qualify tho same 



-oil wi.nl, th.j ui-tirl,- iiiii^-L i:..t. bo repeated: 



L* ingo et ]>ieiix K.'uolou n <!< 

 ..,>t, il lui Ujud !' d 



i.ltft). It" I 



Th vu and jn'oiu Fcnelon hat 

 vi.'ll Mtablufail r.'j/liU to general 

 f(em. 



At then word* h< prtnt4 (o him, 

 the icet aiwi ttndr book. 



(1.) "\Vhi-n two nouns are joined by the conjunction ou, an<l 

 is merely a repetition or explanation of the first, the 

 h< ul.l nut bo repeated: 



The cheek* or tides of th condor's 

 head an) covered with black down. 



They di*tin<juihcd among the 

 nobles the palatine* or yovtrncrt 

 of ji 



Les jinn-* ou iv'itrn do i 



sent converted 'Vim duvet 



BUFFO*. 



On ditinguoit parmi les nobles 

 lOB pulutiuH OU K'.uveruours des 

 , s. J. J. EOUSSXAU. 



80. MISCELLANEOUS REMARKS ON THE USK or THE 



AllTICLE. 



(1.) Tho article is not used before numbers placed after 

 :ues of sovereigns, to designate their order of succession 



[ 27, ()] :- 



Lo\iis diX-hUlt, Charles dix. I Louis the eighteenth, Charlct the 



\ tenth. 



(2.) The French put no article before nouns placed in appo- 

 sition with, or explanation of, other preceding nouns : 



Louis treize, fils de Henri 

 fut bieu different de son 



L tartufe, C0m6dle do Molu-re. 



L;iiii;u-iijn>, c^K-bre poete et 

 prosateur francois. 



Je suis fran9ais, vous dtes 

 americain. 



(3.) If the explanatory word is itself taken in a qualified 

 sense, the indefinite article un is then placed before it : 



Louis the thirteenth, the on of 

 Henry the fourth, was very different 

 from hi* /other. 



The Tartufe, a comedy of ISolicrc. 



Lamartine, a celebrated French 

 poet and prose writer. 



I am a Frenchman, you are an 



Get homme eat tin Francois 

 d'une famille illustre, mais mal- 

 Leureuse. 



Ces messieurs sont des mar- 

 cbauds de Lyon. 



That man is a Frenchman, of an 

 illustrious but im/ortunate family. 



Those gentlemen are merchants 

 from Lyons. 



( -t.) Under tho second rule of this may also be placed the 

 words mentioned in 76, Rules (11.) (12.) (13.) and (14.) : 



une montre d'or, 

 un maitre de dessin, 

 un mouliu & vapeur, 

 une chambro a coucher, 



ratch. 



a drawing- master. 

 a steam-mill. 

 a bed- room. 



(5.) By exception to Rule 2 of this , tho definite article 

 is used, besides tho preposition a, between such nouns as express 

 the vessels, places, etc., in which commodities are generally 

 kept or sold, and the noun expressing such commodities ; but 

 this occurs only when the preposition between the two nouns 

 is a : 



nn marchrf aux chevaux, 

 la lialle au bli ; , 

 la bouteille au via, 

 le pot au lait, 



a horsc-/air. 



the corn-ezchangc. 



-dottle. 

 the milk-jug. 



Nouns referring to vessels, however, admit of being followed 

 by the definite article only when they are preceded by it ; bni 

 when they follow the indefinite article, the preposition a alone 

 must be used : 



le pot au lait, 

 un iint a kit, 



la I>outei11. a IVn-re, 

 Une bouteille a c'ucr.-, 



lh mill; -jug. 

 a milk-jti'j. 

 the ink-lottle. 

 an mk-bottl. 



EEC I: i:\TIVI-: M I !/>< K.XIV. 



THE M ICIiOMCul'E, BIMPLB AND COMI'OUN t> KIFLECTIKO PUI8M. 



I Hollander'! solar microscope, already described, no doubt 

 lunses employed were the uu*l ones, riz., a plano-convex 



H (A, Figs. 1 and 2), which bend* or refracU the ray* of light 

 nearly to a focuu at the alide, , containing the object Sub**, 

 quently the light panne* through two plano-convex leaves, each 

 M)ing of about half an inch focal length, at c c, and <?t in 

 i by the bar and screw at o. To increase the sharpnew 

 of the image, it is usual to insert a diaphragm of metal, K, 

 through which a small hole ha* been carefully drilled, between 

 ;ho two lenses at c ; in fact, it in the same arrangement of lenses 

 used in a magic lantern, only in this case they are of a higher 

 magnifying power. 



Tho adaptation of the diaphragm for the prevention of 

 spherical aberration was used by Dr. Wolhuton in the construe- 

 ;ion of a lens, in which he placed a disc of brass, or other metal 

 [perforated with an aperture), between two plano-convex lenses, 

 and thus constituted one of the most perfect simple microscopes 

 because only those rays that pass through the centre of the lens 

 enter the eye. The Stanhope lens is a good example of the 

 same class of microscope, and in this case the foci of parallel 

 rays of light refracted on one side nearly correspond with the 

 other ; so that any object, like paste eels, placed on one side is 

 seen highly magnified by looking through the other. 



Whenever two lenses are employed together, the combined 

 arrangement used to magnify the real size of any object is 

 called a simple microscope. If, however, the spectral figure 

 formed by one lens or set of lenses is magnified by another lens 

 or series of lenses, then it is called a compound microscope, and 

 is shown at Fig. 3, in which s is the object-glass, o the object 

 in its focus, F tho /eld-glass, and the eye-glass ; s the spectral 

 figure of K magnified by K. 



In alluding to all the optical arrangements required to increase 

 the apparent size of an object by refraction, it has been well 

 said by Mr. Brooke, in his " Elements of Natural Philosophy," 

 that " It is an axiom scarcely appreciated by many microscopists, 

 that in order to obtain the most perfect definition in the image 

 of an object, ' a careful adjustment of the rays incident on the 

 object is not less important than the clear adjustment of those 

 that proceed from the object to the eye.' In many instances 

 the parts of an object will be distinctly defined when it 

 is properly illuminated by an aplanatic pencil (that is, a 

 pencil free from aberration), that would be almost if not 

 entirely lost when the common mode of illumination i* 

 adopted viz., a pencil reflected obliquely from a spherical mirror 

 of short focal length, and which consequently possesses a very 

 large amount of spherical aberration. Any optical combination 

 placed under the object by which a pencil of light may be 

 directed upon it, is called an illuminator, which ordinarily con. 

 sists of a combination of lenses so placed that their common axes 

 may coincide with that of the microscope ; and when properly 

 adjusted, the object and the source of light are the conjugate 

 foci of the combination. When this is the case, the image of 

 the source of light will be superposed on that of the object. 



" When a lamp or gas-burner is the source of light employed, 

 the flame should be protected by a ground-glass shade, for if the 

 object be transparent, an image of the flame itself, when super- 

 posed on that of the object, will almost if not entirely extin- 

 guish it. 



" The best source of light is any opaque, white, unpolished 

 surface, strongly illuminated ; that from a white cloud opposite 

 the sun reflected by a plane mirror, or, still better, internally 

 reflected by a rectangtUar glass j/rism, is of all illuminations 

 tho best ; but as this is rarely obtainable in the murky atmo- 

 sphere of a large city, a plate of plaster of Paris, or a flat sur- 

 face of powdered carbonate of soda, placed beneath the con- 

 denser transversely to the axis of the microscope, and strongly 

 illuminated, forms a convenient artificial white cloud ; but, still 

 better, a plate of white enamel, with a finely-ground surface, 

 the brilliancy of which whan soiled can be immediately restored 

 by washing the surface with soap and water. 



" The light should be placed laterally, and in front of this, and 

 as large a concave silvered reflector as can conveniently be em- 

 ployed should be placed behind the light, so as to accumulate ae 

 much light as possible on the plaster or enamel disc." 



In the above quotation from Mr. Brooke, it will be noticed 



