The program of observations of minor planets at the Goethe Link Observatory

The Indiana program was started in response to an appeal in 1947 from Dirk Brouwer, President of Commission 20 of the IAU, for cooperation to help overcome the effects of the war-time gap in asteroid observations. The 10-inch Cooke triplet lens which we have used is the property of the Cincinnati Observatory. The scale is 120.̎15/mm. Observations were started in 1948 and continued until the retirement of Mrs. Beryl H. Potter in June 1966. Nearly 6300 plates were taken during this period.A micrometer eyepiece on the guide telescope was used to produce a round image of the asteroid and trailed images of the stars. Prior to 1961 a one hour exposure on Eastman 103a—0 plates would show objects almost to the 18th magnitude. After 1961 the plates were slower and the sky brightness increased with the growth of Indianapolis, 10 miles to the northeast. The plates were taken in pairs in immediate succession, and were blinked by Mrs. Potter. She also did a large part of the measuring and supervised the student assistants who participated in the measuring. By the time Mrs. Potter retired, she had found nearly all of the “critical list” objects which could be reached with our equipment.

A sensitive and accurate gel osmometer

1. A bilayer strip, cut from a thin layer of cross-linked polyacrylamide gel cast on to cellulose tissue, forms an open circular loop whose ends are close together. Shrinkage of the gel, in response to the osmotic pressure of a non-penetrating solution, causes a proportional separation of the ends of the loop. This is measured with a microscope and micrometer eyepiece. 2. The resulting effective sensitivity is about 30 times that of the Sephadex-bead osmometer (Ogston & Wells, 1970), i.e. of the order of 5Pa, comparable with that of a membrane osmometer. Use of gel up to 70% (w/v) allows the measurement of molecular weights, as low as 1500 in favourable cases, with an accuracy of 1–2%. The useful range of osmotic pressure is up to 5kPa. A single measurement requires 0.5ml of solution. Equilibration is completed in 20–30min. 3. The method is illustrated by measurements on human serum albumin, ovalbumin, cytochrome c, samples of dextrans, polyvinyl alcohol, and polyethylene glycols 6000 and 1000.

Wing Folding in Lepidoptera

The wing folding mechanism was investigated after a detailed study of the wing base morphology had been made (Sharplin, Canad. Ent. 95: 1024; 1121). Living moths were observed with a binocular microscope equipped with a micrometer eyepiece.The first and second axillary sclerites do not move anteroposteriorly; only the distal half of the wing base is involved in wing folding. The folding muscle originates on the pleural ridge and inserts on the third axillary sclerite. The movement of the third axillary is communicated to the bases of the anterior veins through the median plates. The radial plate rotates around the ventral second axillary sclerite which lies underneath the radial bridge at point p, (Fig. 1). Bending cuticle allows the radial bridge to buckle when the wing is folded. The first median plate ( Ml ) rotates about its articulation ( f ) with the dorsal second axillary sclerite. The distal median plate (M2) passes underneath the second cubitus and is fused to the radius. This connection to the radius restricts the backward movement of the second median plate so that point e instead of following the wider arc eg of a circle with its centre at f, must follow the arc cegd drawn about pivot p. The median plates are bent upwards during wing folding and their effective length is shortened so that they can follow the shallow arc epg. When point e is in position g the posterior margin of the median plates is straight, although the anterior margin remains arched causing the median plates to be buckled, (Fig. 2).

Particle-Size Distribution of Pulverized Snow

A microscopic method for the determination of particle-size distribution of pulverized snow was worked out. The method gives satisfactory distribution curves, presenting the number of particles as a function of their cross-sectional “areas”. The measurements were made by means of a filar micrometer eyepiece, the snow particles being placed on a ruled glass slide, which was submerged in silicone oil to prevent evaporation. The time for the determination of a distribution can be appreciably shortened by estimating the size of the particles instead of measuring them, though the accuracy is not so high in this case.

Particle-Size Distribution of Pulverized Snow

A microscopic method for the determination of particle-size distribution of pulverized snow was worked out. The method gives satisfactory distribution curves, presenting the number of particles as a function of their cross-sectional “areas”. The measurements were made by means of a filar micrometer eyepiece, the snow particles being placed on a ruled glass slide, which was submerged in silicone oil to prevent evaporation. The time for the determination of a distribution can be appreciably shortened by estimating the size of the particles instead of measuring them, though the accuracy is not so high in this case.