ARRANGEMENT OF APPARATUS, ETC. 125 



The sixteenth immersion being erupted, the dry 

 front of the eight will be found to answer admirably 

 when used as in last process. 



AH subsequent operations are conducted in exactly 

 the same manner. 



Dry plates or the wet process may be used, the 

 former if ten times as rapid as collodion requhing an 

 exposure of from one to five seconds. No fixed rule 

 can be given for exposure with sun-light for the rea- 

 sons already mentioned. 



In conclusion we must caution our readers against 

 expecting success at the first trial, unless they have 

 had some previous experience in photography. On 

 this account we recommend the production of nega- 

 tives with an ordinary camera and. lens before at- 

 tempting micro-photography. 



When carrying out the methods here described, 

 avoid speaking or walking in the same or adjoining 

 apartment during exposure as this is very likely to 

 cause vibration of the instruments. 



Too great care cannot be taken to prevent the 

 entrance of actinic light. All instruments must be 

 lined with black velvet. When in position the mi- 

 croscope and Camera should be covered with a dark 

 cloth before the substitution of the plate carrier for 

 the ground glass and subsequent exposure. Every 

 means must be adopted to prevent the entrance of 

 actinic light into the dark room, and while placing 

 the sensitised plate in the carrier as well as during 

 developement, no more light should come through 

 the ruby glass, or exposure of the plate to it be 

 allowed, than shall just enable us to work. 



