i873- 



Light. 



423 



and to whom the tremor of the old model was very annoying. The old 

 pattern has been kept in favour solely by the great care taken in its construc- 

 tion by our leading makers, the slightest defect in workmanship being in this 

 form very apparent, and causing a fatal amount of unsteadiness. It affords a 

 remarkable instance of constructive skill overcoming in a great degree the 



defects of an originally faulty design. That this form should have been ulti- 

 mately adopted by the late Andrew Ross is very remarkable, as his older 

 microscopes, as well as those of Mr. Powell, had the body supported by a con- 

 siderable portion of its length upon a rigid limb.* 



Dr. J. G. Richardson communicates to the " Philadelphia Medical Times" 

 some account of the properties of acetate of potash in temporarily preserving 

 tissues during transmission for examination. The process has been principally 



* Penny Cyclopaedia, vol. xv., p. 187; article "Microscope," by Andrew Ross. A fine 

 specimen of Powell's old construction is in the collection of instruments of the Royal 

 Microscopical Society, 



