260 THE AMEEICAN MONTHLY [November, 



foci, are so nearly identical that no difficulty will be experienced in 

 obtaining sharp definition of any subject if a little care be used. But it 

 may not be amiss to say the student's series of Bausch and Lomb are 

 the best, by all odds, of any I have ever seen or used at all approaching 

 them in moderation of cost. I have numerous i"emarkable examples of 

 their work which I have never seen excelled by lenses of equal powers, 

 no matter what their cost. It certainly is not necessary to go abroad in 

 these latter days to get the best in the optical as well as in many other 

 directions. 



The dry plates for the "• Handy " camera are furnished by the makers 

 in two degrees of sensitiveness to suit every variety of subject. They 

 are readily developed by any of the methods used for gelatine plates, 

 my own preference being given to hydroguinon or a mixture of that 

 with eikonogen, as giving the clearest results, clearest details, and 

 sharpest contrasts with any desired amount of density. Their cost is 

 but twenty-five cents per dozen ; certainly cheap enough to tempt any 

 one to their use. 



In conclusion, a few words upon various printing methods. Pre- 

 suming that every microscopist who ventures into the realms of photo- 

 graphy will do his own printing, a few hints may prove useful. There 

 can be no doubt of the beauty and perfection of a good, properly toned, 

 and finished print upon albumenized paper. This is conceded. But 

 comparatively few amateurs will ever succeed perfectly in the opera- 

 tion of sensitizing the paper and toning the print, whilst most of the 

 " ready sensitized " paper on the market is an abomination and a snare. 

 Therefore discard this method of printing, unless prepared to do first- 

 class work. 



Passing by platinum as being both expensive and uncertain, except- 

 ing in the hands of an expert (although its beauty and perfection cannot 

 be too highly extolled), let us consider for a moment the decided claim 

 of bromide paper, as being the best material for printing in our class 

 of work. Using the smooth surface paper and developing with ferrous 

 oxalate, we get a perfect print rendering the most delicate details with 

 the crispness and clearness of a steel-plate engraving, which indeed it 

 most closely resembles in very many instances. The exposure is made 

 by lamplight, so that one is entirely independent of time or weather, 

 and the finished print is absolutely permanent ; as much so, it is rea- 

 sonable to believe, as a carbon print. If the sheet be allowed to dry 

 spontaneously, it will present the appearance of an ordinary plate en- 

 graving. If a polished surface be desired, all that is necessary will be 

 to float the paper, print side down, upon a sheet of polished hard rub- 

 ber ; to squeeze it into optical contact, removing all superfluous moist- 

 ure, and when quite dry it will peel oft' the rubber plate with a beau- 

 tiful polished surface, greatly increasing the delicacy of detail in many 

 subjects, especially diatoms. Most decidedly my preference is given 

 to this form of printing. 



But there is another method which, at the risk of being laughed at, 

 I am inclined to gently urge. I refer to the ferro-prussiate, or more 

 commonly named " blue prints." This method of printing is tabooed 

 in many instances, "blue prints" being vigorously proscribed in the 

 albums of the Postal Photographic Club, but for all that it has decided 

 advantages and merits for the work we are considering. It is cheap, 



