420 SUMMARY OF CURRENT RESEARCHES RELATING TO 



objective of given aperture increases in the same ratio as the wave- 

 length of the light employed diminishes, it follows that the electric 

 light ought to show delicate details more easily than the yellow light 

 of gas or lamps. 2nd. The si>ecific intensity of the electric light 

 being much more considerable than that of other artificial lights, 

 sufficient illumination is obtained with a pencil much narrower than 

 that which must be employed to obtain the same luminous intensity 

 with gas or diffused daylight. Kays much more oblique can there- 

 fore be used." 



The lamp should be placed in a small box, the cover of which is 

 pierced with an opening. The Microscope is placed on the box, the 

 mirror being turned away from the axis or entirely removed. The 

 light of the lamp is then concentrated by a plano-convex lens and 

 directed into the condenser. 



The use of the electric light also allows the microscopist at any 

 moment to photograph an object in the field, and directions are given 

 for proceeding on the dry plate method. 



Definition of • Natural and Artificial Objects.* — In some "Ee- 

 collections of my Life," T. Baumann says that the difference between 

 a natural and an artificial object cannot be more briefly or more 

 precisely defined than by saying that under the Microscope the natural 

 object is always more beautiful and the artificial one always more 

 imperfect the more the magnifying power is increased. 



Cole's " Studies in Microscopical Science." — Mr. A.C.Cole has 

 projected a weekly j)eriodical under this title " for the use of students, 

 professors and teachers, the medical profession, and others interested 

 in the progress of the natural sciences or engaged in higher educa- 

 tion ... to meet a want, which, even in these days of practical teaching, 

 is felt by every student commencing the study of the natural sciences 

 equally with those who are desii'ous of devoting their leisure to 

 scientific pursuits. 



" It is proposed by means of a carefully prepared and typical 

 object for the Microscojie, together with a drawing and descriptive 

 essay, to supjily students, microscopists, and members of the medical 

 profession, with a ready means for studying, 1. Microscoj^ical biology 

 in all its branches, 2. The physiological and pathological histology 

 of the body. 3. The essentially modern sciences of microscopical 

 palaeontology, mineralogy, and petrology. 



" Subscribers will be entitled to receive every week: 1. A micro- 

 scopical preparation of the highest class and most perfect finish. 

 2. A printed description of the preparation, in which will be noted : 

 a. The literature concerning it. b. The habitat, &c. c. The methods 

 employed in its preparation as a means of study, d. Its principal 

 features, and any necessary additional remarks. 3. A lithographed 

 or engraved di'awing, or diagram, of the preparation, in the execution 

 of which the following details v-ill be most carefully considered and 

 adhered to. a. Accuracy, h. Finish, c. Indication of Natural 

 Size, &c. 



" The preparations during the first year will consist of a series 



* Zeitachr. f. Instrumcnteuk., ii. (1882) pp. 46-51. 



