1889.] MICROSCOPICAL JOURNAL. 249 



been properly adjusted you will see both the image and the point of 

 your pencil, and 3'ou will have no difficulty in following the outlines of 

 the object. You will find the whole process of drawing an object 

 under the microscope becomes as simple as the tracing of a picture on 

 a child's transparent slate. The shading and details can be readily 

 filled in after you have sketched all the outlines. A curious reversal of 

 the image takes place with Beale's reflector which is shown in Science- 

 Gossip for 18S3, p. 365. The effect of this for low powers can be 

 corrected by turning the slide over on the stage. For high ppwers, the 

 thickness of glass slides is too great, and the working distance of the 

 lens too short, to admit of this device being resorted to, but by the 

 time you have got to draw under high powers, you will have made 

 sufficient advancement to be able to disregard the reversal of imasre 



o 



which is inseparable from Beale's camera, and which is no doul^t con- 

 fusing to beginners. 



It is scarcely necessary to say that these devices merely enable you to 

 sketch rapidly, and with perfect accuracy, the relative proportions of 

 an object, and to draw it to scale. A man who can draw will always 

 turn out better finished sketches than a man who can't ; but however 

 much individual skill and tastes may differ, the great aim in micros- 

 copical drawing is, after all, simple accuracy, and this must be the 

 chief study. '' I take it," says a writer on the subject, '• that the first 

 requisite of a microscopical drawing is exactness and truth. Beauty is 

 a secondary thing." {Science-Gossips 1SS4, p. iS.) " No other branch 

 of art," says another writer, "can be approached with a keener or 

 deeper sense of the absolute necessity of close and conscientious obser- 

 vation. The fact must never be ignored that a few rapid lines from 

 dii^ect observation produced on the spur of the moment possess an in- 

 terest of a most appreciable character. This acquirement is not beyond 

 the capability of the meanest tyro, soon discovered and realized when 

 he cultivates the habit of having a drawing block, pen, and pencil as 

 adjuncts to his instrument." {Science- Gossips 18S3, p. 266.) I would 

 only add that your proficiency as a draughtsman will entirel}' depend 

 on your own perseverance, and on continued practice. There is no 

 " royal road " to the acquirement of the art whose claims I urge on 

 your attention ; you must make yoiu^ minds up to mount to success on 

 failures beaten under foot. 



Passing on now to micrometry — the measuring of microscopic ob- 

 jects — let metellyou Leeuwenhoek, the father of microscopical research, 

 worked in this branch of our subject — a proof of the early recognition 

 of its importance. His micrometric scales were grains of glass-grind- 

 ers' sand, and hair from his own beard. He speaks of animalcules which 

 were some thousand degrees less than a grain of such sand as he used. 

 He also tells us that he had a plate of copper, with many lines engraved 

 on it, dividing it into a number of small ecjual parts. Determining how- 

 many of these parts were covered by the diameter of a hair, he next com- 

 pared the hair with the minute vessels, probably tracheae, which he 

 measured with the result, so he says, that the diameter of a hair was 450 

 times greater than that of the vessels measured by him. Such meas- 

 urements are vague ; but though our own precise methods are vastly 

 in advance of Leeuwenhoek's, we must never forget that he did a great 

 deal of really good work with the inferior appliances at his disposal — 



