1895. NOTES AND COMMENTS. 5 



A full notice of him must be deferred to our next number. One of his 

 recent acts was to send the following letter to the Irish Naturalist : — 



" For some time I have had it in contemplation to exhibit in a 

 suitable part of the Museum a collection of portraits of persons 

 identified with the progress of science in Ireland. Quite recently a 

 number of portraits having become available for this purpose, and 

 others, as the result of special correspondence, having been presented 

 or promised, the time is now close at hand when the collection can be 

 placed on view. I therefore desire to make known through the pages 

 of the Irish Naturalist, that contributions and loans to this collection 

 of portraits of eminent and acknowledged men of science belonging 

 to the above denomination will be gratefully accepted. Circum- 

 stances have rendered it desirable that no restriction whatever should 

 be put upon the style or nature of the portraits so contributed, no 

 funds being available for securing uniformity. Hence we have 

 decided to accept oil paintings, lithographs, etchings, or photographs, 

 and to exhibit them as received, save that suitable frames will be 

 supplied when needed. Portraits of mathematicians, astronomers, 

 physicists, meteorologists, geologists, botanists, zoologists, anti- 

 quarians, and numismatists will be arranged in separate groups. In 

 the cases of those who are deceased, short biographical notices will 

 be attached to the portraits." 



We trust that this application will have the desired effect, and 

 at the same time we suggest to those who will now carry it out as a 

 memorial of their departed chief, that they might include autograph 

 letters or manuscripts, as such are found useful in the identification 

 of labels and other memoranda associated with specimens. 



Weights and Measures. 



The American Metrological Society has the praiseworthy object 

 of advocating a rational system of weights and measures. To that 

 Society as well as to our readers, we commend a treatise upon 

 measures, recently published in London by Mr. Wordsworth 

 Donisthorpe. In that he traces the past history of our existing 

 standards and advocates a new system based upon the metric scale, 

 by which, of course, the measures of length, surface, and volume 

 would be correlated. Incidentally in his book he mentions some 

 ingenious comparisons that may be found useful by our readers. All 

 of us who use the metric system in scientific work, unless we have a 

 very extensive habit of measuring, find it more or less difficult to 

 realise actual dimensions when the metric names are applied to them. 

 We all know what an inch is ; how many of us could draw on paper 

 a line of a millimetre or of a decimetre ? 



The millimetre, Mr. Donisthorpe says, is the length of the letters 

 a. c. e. m., etc., in nonpareil type. The centimetre is a trifle less 

 than the diameter of the little red wafers used by lawyers as seals 

 opposite the names of the signatures upon a deed. The decimetre is 

 within a sixteenth of an inch of the hand used in measuring horses ; 

 that is to say it is nearly four inches, the width of an average man's 



