There are used practically skyline cables of complicated structure, three (Y-type) or more cables (Star type) of which are crossed at a point of space and, recently, the cable system of Y-type, one wirerope of which is used as a skyline cable and the other wireropes are used to move a supporting point of it transversely, has appeared, for skidding timbers overhead on the ground of Δ type. The reliable theory, however, on the skyline cable of this type, has not yet completed.
A remarkable character of the skyline cable of that type, differing from the usual one, is that the distances between the supporting points and the cross point of the sky-line cables corresponding to the span length and the angles of horizontal inclination of them, are not fixed, but changed by the mutual interactions of the skyline cables. This study was carried out to develop a fundamental theory of the skyline cables of this type and, as the results, a method of accurate calculation of the tension of the skyline cables was established and the conditions ensuring the safety of it were presented.

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According to the results of the experiments on the relation of the moisture content of wood and the relative air humidity to the decay of Japanese red pine wood due to the attack of four species of brown rot fungi, G. abietinum (BULL, ex FR.) KARST., G. trabeum (PERS. ex FR.) WURR., G. subferrugineum (BERK.) BOND. et SING. and G. sepiarium (WULF. ex FR.) KARST., the decay occurred at a wide range of moisture content between 10_??_20% and 250%. In so far as the results of the present investigation, the maximum decay due to G. abietinum and G. trabeunz took place at the moisture content ranges of 105_??_115% and those due to G. subferrugineum and G. sepiarium occurred betweeen 115% and 135%.
The moisture content of wood blocks increased with the rise of relative air humidity, especially at the humidity of more than 80%. A similar result was obtained in the case of wood decay, while the wood blocks which had been incubated for 90 days at the relative humidity of 51% showed no signs of decay.
From the above results, it may be considered that the wood block containing less than 15% moisture is safe from the attack of these fungi and that the danger point for fungal attack may lie at about 15% moisture content and 80% humidity.

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We have known that the gypsy moth (Lymantria dispar LINNE) and the camphor silk moth (Dictyoploca japonica BUTLER) are the most important defoliator of the broad leaf stand and sometimes the former gives the greatest damage to all broad leaf forests and some needle leaf forests, the latter gives some damage to the japanese chestnut tree (Castanea crenata S. et Z.) in Japan.
In this report, the author deals with the results of the individual breeding of the gypsy moth and the camphor silk moth that feed on Quercus acutissime CARR. (the former) and Castanea crenata S. et Z. (the latter). These investigations were conducted from 1955 to 1957, and the gypsy moth was bred in 1956 and 1957, the camphor silk moth in 1955.
In order to know the correlation between the feeding quantity and the amount of the frass, the author measured the feeding broad leaf area, its dry weight and the dry weight of the frass on twenty individuals every year.
The results obtained from the investigations were as follows:
1) The gypsy moth hatched out from late in March to the middle of April and after the passing of the larval stage of about seventy days they pupated late in June. The pupal stage was about 11_??_15 days. Meanwhile, the camphor silk moth hatched out in April and began to pupation immediately after the larval stage of about sixty days. Its pupal stage was about one-hundred days and the emergence began at late in September.
2) The total feeding leaf area at the larval stage was 700_??_1, 100 cm² at male and 1, 100_??_1, 800cm² at female (gypsy moth), and 2, 000_??_3, 300cm² at male and 2, 700_??_4, 000cm² at female (camphor silk moth). That is, its feeding leaf area was very various at male and female.
3) The feeding quantity at the last instar was the greatest, namely, in comparison with the total, it amounted to about 60_??_70% at the gypsy moth, about 70_??_80%, at the camphor silk moth.
4) The total number of the frass evacuated at the larval stage was counted about 1, 500 at the gypsy moth, about 1, 700 at the camphor silk moth on an average, and its difference between male and female was not evident at the total number.
5) The correlations between the feeding quantity and the amount of the frass were shown with the straight line on the logarithms, that is; gypsy moth:logW=0.8297logD+0.01225 logW'=0.8681logD+0.60078 camphor silk moth: logW=0.8786logD-0.19007 logW'=0.9341logD+0.34470

W: the leaf area of Quercus acutissima CARR. and Castanea crenata S. et Z. in cm2

W': the dry weight of Quercus and Castanea in mg

D: the dry weight of the frass in mg
These correlations could be applied to the dead individual on the larval stage, male and femals as well as the case of the pine caterpillar.

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There are several investigations which have been done to control soil insects by applying the granulated aldrin. This article is a result of preliminary experiment to know the effectiveness of aldrin in different size of granules when applied to the white grub in an afforested field of coniferous trees.
Experiments were carried out in the following various cases to the second instar larvae of May beetle, Anomala rufocuprea.
1) Four kinds of the size of granulated aldrin were made by sieving with meshes of 8_??_10, 12_??_20, 40 and 60, each of those contained 5% aldrin. Each quantity of 5g of these materials was mixed to the air dry soil of 17kg. On the other hand the dust of powdered aldrin was used as a check. Treated soil kept in wire screen cages was buried in the field and left for the test in natural condition. The effects of aldrin were observed by each cases taking the sample (1.5kg weight of treated soil) with stated intervals in 774 days.
2) The soil contained aldrin of the above mentioned rate was kept under 15, 20 and 25°C in constant temperature respectively and the test was carried out under each condition to know the effect of different temperature. After 118 days the effects of aldrin of these treatment soil were tested under 15°C constant temperature.
3) The insecticidal effect of granulated aldrin in soil on newly laid eggs of May beetle was tested in each of the soil of item 1) after about 8 months.
From these experiments above mentioned items we have got the following conclusions.
a) Smaller size of granules of aldrin was more effective than the larger one. The toxity of these treated aldrin was not reduced during nearly two years.
b) The toxity was more effective under higher temperature. The effectiveness was higher in the case of smaller size of aldrin in each temperature according to the tests of 1 st, 2 nd and 3 rd times. While the dust and 60 meshed aldrin granules were inferior to the other granulated aldrin under the similar constant temperatures.
Considering on the above experiments we can expect the more effective and durable toxities by using aldrin and the smaller sized particle of aldrin will be more effective to control the white grub practically.
c) The action of aldrin was not so evident to obstruct the hatching of the egg, while it was very evident to control the just hatched larvae.

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