1884.] 



MICROSCOPICAL JOURNAL. 



35 



the hands of competent and experi- 

 enced observers. 



Certificates stating the errors should 

 accompany each micrometer exam- 

 ined. Makers of micrometers, or 

 those who sell them, could then offer 

 for sale micrometers with the certifi- 

 cates, adding the cost of the certifi- 

 cates to the price of the micrometers. 

 This would be a great convenience to 

 purchasers, obviating the necessity of 

 sending their micrometers away to be 

 compared, which involves some risk 

 in transportation. 



Now that a standard micrometer 

 has been adopted and the whole mat- 

 ter finally settled, it may not be inap- 

 propriate to refer to our own connec- 

 tion with the movement which has 

 resulted so satisfactorily, and to call to 

 mind a few circumstances of interest 

 in connection with it. The subject 

 was first brought before the Society 

 by the editor of this Journal at the 

 Indianapolis meeting. At that meet- 

 ing the matter was referred to a com- 

 mittee, and since then we have taken 

 no active part in the discussions be- 

 fore the Society, although our interest 

 in the matter has never failed. We are 

 especially well pleased to know that 

 the unselfish and meritorius labors of 

 Prof. W. A. Rogers in this field are 

 receiving from the Society due, though 

 tardy, recognition. 



Some of our readers will remem- 

 ber that there was considerable dis- 

 cussion about the unit to be adopted 

 by the Society. The unit proposed 

 by ourselves was the j^ mm. for the 

 small divisions of the standard, and 

 *^^ To^pTT "111''- as the micrometric 

 imit,* in which measurements were 

 to be expressed. No special credit is 

 due for this proposition, for it was a 

 natural outgrowth of the requirements 

 of the time. Yet it was amusing to 

 notice the opposition aroused. Passing 

 over the arguments directed against the 

 micron unit and in favor of some di- 

 vision of the inch, it will be remem- 

 bered that when the y^-^ mm. was 



*Am. Quart. Micr. Journ., I, 235. 



proposed it was roundly criticised as 

 being too small, and the New- York 

 Society, after commending it, was led 

 to retract resolutions passed in its fa- 

 vor, without, as we believed at the 

 time, due consideration. Neverthe- 

 less, when the matter was finally con- 

 sidered with care, the -^^ mm. was 

 found to be not too small but too large 

 for convenience as a unit, and the y-jVo 

 mm. or mici'on was finally adopted. 

 The standard is precisely what was 

 recommended by us more than five 

 years ago. 



o 



Microscopical Material for 

 Distribution. — We have received 

 ninety applications for oyster spat, and 

 quite a large number for Barbadoes 

 polycystina. The whole of the oyster 

 spat has now been distributed among 

 subscribers. Every applicant has, 

 we trust, received a sufficient quantity 

 to make two or more good mounts. 

 It is probable that some have been 

 disappointed with the small quantity 

 sent, but all of the best material, with 

 the exception of a very small amount 

 reserved for personal use, was divided 

 up as evenly as possible and sent 

 away. We have still a very small 

 quantity of inferior material reinain- 

 ing, which we do not wish to send 

 out, although with care it might be 

 utilized. 



We have to announce that the sup- 

 ply of Barbadoes earth for distribution 

 is also exhausted. Each of the pack- 

 ages sent out contained sufficient ma- 

 terial to repay the trouble of cleaning. 

 The best process of treating the ma- 

 terial will be given next month, as we 

 have no room for it in this number. 



Some other specimens, principally 

 deposits containing diatoms from cele- 

 brated localities, will soon be offered 

 to subscribers to this Journal. Fur- 

 ther announcement will be made next 

 month, and the localities of the de- 

 posits named. 



Staining Nuclei. — The columns 

 of this Journal contain a great va- 

 riety of formulae for staining and 



