i8 



THE AMERICAN MONTHLY 



[January, 



only necessary to quote the following 

 from the paper referred to : — 



" It will be seen, however, that the 

 plate makes a better record for uniformity 

 than any other micrometer examined. In 

 width of space it lies between the Fasoldt 

 Y^-g- inch and -^-^q-^ inch groups : the de- 

 viation from the mean in the first is some- 

 what more than one per cent., while in the 

 new Rogers it is only about eight-tenths 

 of one per cent., and this, too, with only 

 two measurements of each space, against 

 five for the Fasoldt." 



Finally, it seems hardly worth while to 

 refer to the intimation contained in your 

 notice that possibly there may have been 

 a desire to "demonstrate the imperfec- 

 tions in Professor Rogers's rulings" in the 

 selection of a "particular micrometer" 

 for measurement. The plate used was 

 one which was purchased of Professor 

 Rogers several years ago by Professor 

 Tuttle, and was the first of its kind ruled 

 by him. Just what plate it is, is perfectly 

 well known to Professor Rogers, and, as 

 far as the writer knows, its " tale " is cer- 

 tainly " plain, unvarnished," and, I may 

 add, devoid of any special interest. 



No one has higher respect for the 

 most excellent micrometric work of Pro- 

 fessor Rogers than the writer, and no 

 one has for him a warmer personal 

 regard. — Yours respectfully, 



T. C. Mendenhall. 



[If the reader will refer to our article on 

 page 236 of the December number, he 

 will see that our remarks were not calcu- 

 lated to do injustice to anybody. We 

 still regard our question, " Why the mea- 

 surements were published at all ? " as a 

 pertinent one, in view of the statement 

 by Professor Mendenhall that the plate 

 measured " does great injustice " to Pro- 

 fessor Rogers. We can understand, and 

 so can all others who are familiar with 

 Professor Rogers's work, that that imper- 

 fect plate does not indicate in any way 

 "the regularity with which such plates 

 run." But how can the great mass of 

 readers know this ? No matter what the 

 intentions of the writer may have been — 

 and surely we do not wish to misinterpret 

 them — we do know that there are some 

 persons who are only too glad to use the 

 published results to show that Professor 

 Rogers's work is not uniform, and, per- 

 haps, we are a httle impatient when we 

 see anything that seems in the least un- 

 fair in this connection. 



Professor Mendenhall has quite mis- 

 construed our language when he alludes 



to our "intimation" of a desire, on his 

 part, to "demonstrate imperfections in 

 Professor Rogers's rulings, etc." We 

 made no such intimation whatever, as 

 any one can readily see. But we have 

 been informed that a certain plate by Pro- 

 fessor Rogers, known not to be one of 

 his best or latest ones, has been used at 

 Albany to demonstrate the superiority of 

 Mr. Fasoldt's rulings over his own. It is 

 such unfairness that receives our con- 

 demnation at all times, and we can only 

 hope that the rumor is unjust to Mr. 

 Fasolt. — Ed.] 



To THE Editor. — Having studied, 

 during the past summer, some of the in- 

 fusoria of this locality, I send you a list 

 of the same : 



Fresh Water Alg^. — Hyalotheca 

 dissiliens Desmidiiun Sivartzii, Micras- 

 terias denticulata and tr 11 neat a; Etiast- 

 rum oblonguni, Cosmariiifn tnargarli- 

 fenun, Closterium moniliferum, Stauras- 

 tnun alternans, vestitiem, paradoxutn 

 bracheatiini ; Pediastriun teiras, bira- 

 diatwji, pcrtusiini^ Spirogyra and 

 Vol vox Glob at or. 



DiATOMAC^. — Cocconema lanceola- 

 tu7n, Synedra capitata., ulna, Gornpho- 

 tienia capitatutn, Siirriella, ovata, Navi- 

 ciela, several species. 



Rhizopoda. — Amoeba prote7is, verru- 

 cosa^ radiosa, villosa, Dijffiugia Pyrifor- 

 jm's, urceolata, lobostonta, corona, con- 

 strict a, A reel la vulgaris, niitrata, Eu- 

 glypha alveolata, ciliata, Asstilina semin- 

 uhim, Trine/na enchelys, Actinophrys 

 Sol, Acanthocystes. 



Infusoria. — Cerateum lofigicorne, 

 Melodinium uberrutiiutn, Paramecium 

 aurelia, Coleps hirtus, Colpoda cucullus, 

 Tracltelocerca versatills, Lacrytnaria, 

 cohnii, Spirostomium ambigufn or Heter- 

 otricha, LeucopJirys virens, Stentor poly- 

 niorphus, Stentor iiiultiformis, Gyrocoris 

 Oxyura, Vorticella nebulifera, putri- 

 num, microstoma, epistylis, Ophrydium 

 echornu, Kerona polyporum, Gastrostyla 

 steinii, Trichoda lyceus, Podophrya, 

 Qttadripartita, Acineta Mystacina, No- 

 teus, quadricortiis, BracJiiomis Pala, 

 Mornocerca rattus, Dinocharis pocillunt, 

 Stephanops lajnellaris. 



These are a few of the multitude 

 of the creatures that abound in the 

 lakes and ponds in this locality. Not 

 having access to a good work on the 

 Algae and Diatomaceai there are many 

 forms that I cannot identify. — Yours, etc., 



J. W. 



Minneapolis, Minn. 



