398 Notes and Memoranda. 



Mr. Wenham described a modification of his plan of combining 

 two prisms for binocular vision with, high powers, designed by Mr. 

 Abren ; and Mr. Jabez Hogg exhibited the spring clip described 

 in our Notes and Memoranda. Mr. How showed his new student's 

 microscope, which is described in our Notes and Memoranda. 



NOTES AND MEMORANDA. 



Measuring- Small intervals and Counting Meteors. — The Eev. "N". J. 

 Heineken has sent us two letters on the above subjects. He says that an ordinary 

 spring tape measure — one yard — drawn out and suddenly released, springs back in 

 a quarter of a second, and it may be arrested so as to mark smaller divisions. He 

 says that although the velocity is not strictly uniform, it is near enough for ordi- 

 nary purposes. By attaching a weight to the tape, and allowing it to spring ver- 

 tically, he thinks the motion might be regulated. In counting the meteors in the late 

 splendid display, he used " one of Perkins's old pedometers." Each step is regis- 

 tered in this instrument by pulling a string, and Mr. Heineken holds it in one 

 hand, and pulls the string with the other, each time a meteor appeared. 



How's New Student's Microscope. — When a number of respectable firms 

 compete in the construction of cheap microscopes, it naturally happens that they 

 distribute the inevitable expenditure in different directions, and it would be im- 

 possible to do justice to Messrs. Beck, Pillischer, Baker, Collins, etc., without 

 instituting an elaborate comparison of their several patterns. Mr. How now 

 comes forward with a new pattern, which deserves a high place amongst cheap 

 instruments. The brass-work is very good, the stage has a new arrangement for 

 facilitating its motions, which is one of the best we have seen. The upper part is 

 held to the lower one with springs, offering a convenient resistance, and it can be 

 moved backwards, forwards, up and down, or in slanting directions. Its action 

 resembles that of the magnetic stage in smoothness, etc., but it is far more 

 reliable. A dividing object-glass is supplied with this instrument, giving with ten 

 inches of tube and a Ross A eye-piece, powers of about 45, 100, and 130. The 

 eye-piece employed by Mr. How is of higher power, bringing the magnification 

 to about 200 with the whole combination. Still deeper eye-pieces can be used 

 satisfactorily. The powers are very well finished and corrected. They are of 

 English make, and differ from higher-priced ones in having much smaller angles 

 of aperture. This is a legitimate mode of lessening cost, and small-angled powers 

 being much more easy to manage, and having great penetration, are the best 

 fitted for beginners. All the ordinary objects (excluding lined tests, for which 

 the apertures are not sufficient) are beautifully shown with Mr. How's cheap 

 objectives, and as his student's microscope is made with the universal screw, 

 other objectives may be added when required. 



The Wire Spring Clip eor Microscopic Objects. — Mr. Curtis (of Mr. 

 Baker's establishment), has improved upon a clip for holding down the covering 

 glass when preparing microscopic objects, which was originally devised by Dr. 

 Maddox. It is made by bending an elastic brass wire, so that it will open and 

 shut like the common letter clip. The cover is pressed down by a small cork, and 

 held in its place while cement is applied and allowed to dry, or Canada balsam 

 allowed to insinuate itself by capillary attraction. Mr. Jabez Hogg informs us 

 that he has found it " extremely useful in mounting alga?, tongues of mollusca, 

 etc., in glycerine jelly, or similar preparations." We can also speak well of it from 

 personal use, and its price per dozen is very small. 



The Portable Horizontal Slide Cabinet and Covered Opaque 

 Slide. — These two excellent inventions of Mr. J. Piper, a member of the Old 

 Change Microscopical Society, will, we believe, be sold by the prinoipal makers 

 and dealers in microscopes. The " Cabinet" is a neat box, containing six strong 



