136 



THE AMERICAN MONTHLY 



[July- 



gaged in preparing a series of " Types 

 of the Synopsis," of which he says in 

 his prospectus : — 



" The figure the most exact, the 

 description the most complete, does 

 not give so perfect a knowledge of an 

 object as does the view of the object 

 itself. The author of the " Synopsis " 

 believes, therefore, to render service 

 to diatomop/iiles, and more especially 

 to debutantes^ by publishing a series 

 of microscopical preparations repre- 

 senting the principal types of the 

 " Synopsis " and elucidating the spe- 

 cies, etc. 



There will be about 350 prepara- 

 tions, containing 400 or 500 forms. 

 Besides diatoms of Belgium there will 

 be specimens from fossil deposits, 

 such as the Rappaneck, Barbadoes, 

 Richmond, etc., which have been fig- 

 ured in the plates. 



Twenty-five preparations in a neat 

 case, will be published each month, 

 beginning in July. The price for 

 each set of 25 ^^reparations cannot be 

 announced at this time. The price 

 in Belgium is, or rather has been, 25 

 francs, to which must be added the 

 duty, and transportation charges 

 which cannot be estimated. Orders 

 may be sent to the Editor of this 

 Journal who will fill them at the low- 

 est price possible to subscribers to the 

 Journal. 



Oculars. — If a number of eye- 

 pieces are subjected to examination, 

 it will probably be found that many 

 of them are far from being as perfect 

 as they should be. Take a piece of 

 paper ruled in small squares and ex- 

 amine it by looking at it through the 

 oculars reversed. Probably many of 

 the oculars will show the scpiares great- 

 ly distorted. This is mainly owing to 

 the fact that makers have departed 

 from the proper formula for placing 

 the lenses in relation to their respec- 

 tive focal lengths. There is no doubt 

 greater attention will be given to the 

 construction of oculars in the future, 

 for the subject is already receiving 



attention in England. Mr. Bulloch 

 has measured the focal lengths of 

 many oculars, and no doubt he has 

 records in his possession which would 

 tell to what extent the original, and 

 also the best, formula has been de- 

 parted from, in setting the lenses. 



A New Fine-Adjustment. — Mr. 

 VVenham has devised an entirely new 

 iine-adjustment for microscopes, which 

 we can most unhesitatingly say seems 

 to be the acme of perfection for the 

 purpose. It is devised on a totally 

 new principle, and has been applied 

 to the large Ross stand, now in the 

 possession of Mr. Frank Crisp. We 

 are not yet at liberty to explain the 

 mechanism, but our readers will hear 

 more about it at an early day. 



A " Scientific Evening." — On the 

 evening of May 2d, the Royal Micro- 

 scopical Society, of London, held what 

 is known as a " scientific evening " at 

 King's College. The scientific even- 

 ings are distinguished from the regu- 

 lar meetings by the informal nature of 

 the proceedings. These evenings are 

 designed to affoid an opportunity for 

 the members of the society to examine 

 objects on exhibition. To avoid over- 

 crowding, visitors are not admitted, 

 except by the consent of the President 

 and Council. 



As the editor was so fortunate as to 

 be present on the occasion referred 

 to, he has prepared a few notes upon 

 some of the objects exhibited. But 

 in the beginning it may be said, that 

 the plan of having certain evenings 

 set apart for the sole purpose of ex- 

 hibiting objects especially for the 

 mutual benefit and instruction of mem- 

 bers, is worthy of adoption by similar 

 societies in this country. It will read- 

 ily be understood that when objects 

 are selected for public exhibition, 

 quite different considerations will in- 

 fluence their choice than those which 

 would prevail were the selection to 

 be made for the edification of persons 



