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Electrical steering of vessels
660
CURRENT TOI'ICS.
[J. F, I.
Electrical Steering of Vessels. H . L . HIBBARD. (Amer.Inst. Ele¢. E~tgin. Proc., xxxiii, 7o3.)--The modern steam steering gear is briefly described; among its disadvantages the author mentions: ( I ) Long lengths of steam piping and lagging, and rises in temperature of spaces through which the piping passes. (2) Wastage of steam, as steam steering gear takes full stroke, and the valve setting is often such that steam is always blowing through the engine. (3) The engine must be designed for the maximum work required of it,--i.e., when the rudder is at the maximum angle. (4) Severe stresses on reciprocating parts due to sudden decrease of load when the rudder returns to the central position. Mechanical connections from the bridge to the engine valve are a continual source of trouble. Against these the advantages of the electrical drive are : ( I ) Reduction of weight and space occupied by driving mechanism. (2) Suppression of heat in compartments. (3) Elimination of accidents due to burst steam pipes. (4) Reduction of vibration and noise. (5) More efficient mechanism, and the overload capacity of the motor can be used in extreme positions of the rudder. (6) Simplification of the control from the bridge. (7) Increase in rapidity and accuracy of response of the rudder to movements of the controlling mechanism. A short description is given of the early electric gears, and a full description of the recent equipments put into United States battleships, including special contractors for the automatic control of the motor. The method is given for calculating the horse-power required to be installed.
Paper Pulp in the United States. V . E . NUNEZ. (Papier[ab., xii, Festheft, 4 I . ) - - T h e sources of supply for paper pulp are diminishing so rapidly that new sources must be sought for. In ten years, from 19oo to 19o9, the consumption of pulp-wood in the United States increased by IOO per cent., the increase in home-grown spruce being 35 per cent. and in imported spruce 162 per cent. At present only one-third of the pulp-wood consumed in the United States is home-grown, and the present supplies in this country will probably be exhausted in thirty years. On the other hand, much progress has been made in the utilization of other species of wood which have hitherto been considered inferior for pulp-making. Balsam fir has been found to be a fairly satisfactory substitute for spruce in the manufacture of mechanical pulp for newspaper, while jack-pine and hemlock yield lower-grade mechanical pulp suitable for cheap qualities. Tests are being made with several other varieties of wood available in large quantities in the Western States. The inferior woods are preferably ground in admixture with spruce; fir wood tends to give a free coarse pulp of inferior color to that of spruce ; the yield per cord is less, owing to the density of the wood. In the south progress has been made in the utilization of lumber waste, chiefly from long-leaf pine, for the manufacture
CURRENT TOI'ICS.
[J. F, I.
Electrical Steering of Vessels. H . L . HIBBARD. (Amer.Inst. Ele¢. E~tgin. Proc., xxxiii, 7o3.)--The modern steam steering gear is briefly described; among its disadvantages the author mentions: ( I ) Long lengths of steam piping and lagging, and rises in temperature of spaces through which the piping passes. (2) Wastage of steam, as steam steering gear takes full stroke, and the valve setting is often such that steam is always blowing through the engine. (3) The engine must be designed for the maximum work required of it,--i.e., when the rudder is at the maximum angle. (4) Severe stresses on reciprocating parts due to sudden decrease of load when the rudder returns to the central position. Mechanical connections from the bridge to the engine valve are a continual source of trouble. Against these the advantages of the electrical drive are : ( I ) Reduction of weight and space occupied by driving mechanism. (2) Suppression of heat in compartments. (3) Elimination of accidents due to burst steam pipes. (4) Reduction of vibration and noise. (5) More efficient mechanism, and the overload capacity of the motor can be used in extreme positions of the rudder. (6) Simplification of the control from the bridge. (7) Increase in rapidity and accuracy of response of the rudder to movements of the controlling mechanism. A short description is given of the early electric gears, and a full description of the recent equipments put into United States battleships, including special contractors for the automatic control of the motor. The method is given for calculating the horse-power required to be installed.
Paper Pulp in the United States. V . E . NUNEZ. (Papier[ab., xii, Festheft, 4 I . ) - - T h e sources of supply for paper pulp are diminishing so rapidly that new sources must be sought for. In ten years, from 19oo to 19o9, the consumption of pulp-wood in the United States increased by IOO per cent., the increase in home-grown spruce being 35 per cent. and in imported spruce 162 per cent. At present only one-third of the pulp-wood consumed in the United States is home-grown, and the present supplies in this country will probably be exhausted in thirty years. On the other hand, much progress has been made in the utilization of other species of wood which have hitherto been considered inferior for pulp-making. Balsam fir has been found to be a fairly satisfactory substitute for spruce in the manufacture of mechanical pulp for newspaper, while jack-pine and hemlock yield lower-grade mechanical pulp suitable for cheap qualities. Tests are being made with several other varieties of wood available in large quantities in the Western States. The inferior woods are preferably ground in admixture with spruce; fir wood tends to give a free coarse pulp of inferior color to that of spruce ; the yield per cord is less, owing to the density of the wood. In the south progress has been made in the utilization of lumber waste, chiefly from long-leaf pine, for the manufacture