PREFACE TO THE SECOND EDITION. 



In presenting the second edition of this work to the public, 

 the Author begs to oiFer his thanks for the favourable reception 

 the former edition has met with. He trusts that the present, 

 from the numerous additions made to it, will be found more 

 worthy of notice. 



It having been objected, that no mention was made of foreign 

 microscopes in the first edition, this seeming omission is reme- 

 died by the description of all the best instruments now manu- 

 factiir'ed by our continental neighbours. The Author begs to 

 offer his sincere thanks to those friends who have kindly aided 

 him during the progress of the work, and especially to Mr. 

 Lister and Mr. Jackson, for their revision of the whole of the 

 former edition. 



32, Blandpoed Sqdaee, 

 December, 1851. 



