nitrification of the soil and changes taking place in the carbon constituents ; 

 but it is especially valuable in noting some of the diseases of plants, such as 

 those caused by the ravages of fungi and minute insects. (Many examples 

 of diseases occurring amongst corn, grass, fruit, potato and other vegetable 

 crops, were mentioned). With respect to agricultural and gardening 

 operations, further aid may be given by microscopy in the study of fertili- 

 sation and germination, and also in the examination of many animal 

 organisms injurious to plant life. To the timber merchant, joiner, carpenter, 

 cabinet maker, and builder the microscope is of use in noting unhealthy 

 conditions due to fungoid growths, &c. (Dry rot attacking the timber of 

 buildings and fungoid growths injurious to growing trees were described). 



The microscope may be a still further guide to builders in the examination 

 of the mineralogical constituents of buOding stones, and in the same way it 

 may be often serviceable in examining materials used for road making, 

 paving, &c. As shown by elaborate experiments on the devitiification of 

 glass made by Messrs. Douglas Herman and Frank Rutley, and communi- 

 cated to the Royal Society, microscopy can throw much light upon changes 

 taking place in glass owing to different circumstances of treatment, and the 

 same experiments have an important bearing on the study of the formation 

 of some minerals. Jlicroscopy is also serviceable in practical mineralogy, 

 and capable of detecting mineralogical constitution where chemistry fails. 



It is also serviceable to the brewer in noting the purity of the air in the 

 fermenting room, the nature of the water, the quality of the ferment, 

 including the presence or absence of organisms that cause unhealthy 

 fermentations ; and in the same way it is useful to the distiller, and others 

 who have to work with saccharine liquids, such as the sugar refiner. In 

 the mechanical arts, microscopes have been employed with advantage in 

 making delicate levelling operations; also in noting causes of difference in 

 the efficiency of tools, consequent on the character of the materials of which 

 they are made. (Examples of comparators, levelling instruments and 

 callipers were shown ; and also of good and faulty tools, and the work done 

 by them). Dr. Sorby has shown the importance of the microscope in noting 

 the characters of iron and steel; and Dr. H. Wedding has described the 

 microscopical examination of a compound armour-plate, and states that the 

 different varieties of iron and steel used in its consti-uction could be 

 recognised without difficulty. And I have myself found microscopical 

 examination very useful in noting the character of the metal used for 

 shafting, bearings, coatings, &c. 



One other use may be mentioned, viz: in connection with the legal 

 profession in the examination in doubtful cases of handwriting, ink, and 



