English: From the article:

"Of the features mentioned above the most important is the full iron plate in combination with the tuning pin bushing, as shown in one of the accompanying illustrations. In the earlier pianos, and in many of the cheaper pianos of the day, the metal plate extended only to the under side of the pinblock. The pins were driven directly into the block, and under the pull of the wires there was a tendency for the pinblock to crush down through the fibers of the wood, enlarging its hole and failing to keep the strings up to pitch. Another method is to carry the plate at a reduced thickness over the face of the tuning block, so as to allow the outermost bearing point of the pin of the wood to be brought a little closer to the point of attachment of te strings. In this case also there is a tendency for the tuning pin to sag until it bears upon the lower edge of the thin iron plate covering. The first scientific attempt to investigate the pinblock problem and provide a thoroughly mechanical means for holding the tuning pins up to their work was made about a third of a century ago, when the Mathushek Company adopted the excellent construction shown in the third of our figures. They realized that the only satisfactory way to take the combined pull of all the strings was to transmit it as quickly as possible to a metal frame or plate of specially stiff construction. Accordingly they designed the plate shown in the accompanying illustration, which is not only of extra thickness throughout, but is stiffened by deep ribs, so disposed as best to meet the heavy strains imposed. The plate was carried clear over the face of the block, and its thickness at the face increased to about 1 inch. The holes are drilled directly through the plate and they are made sufficiently larger than the pin to allow of the insertion of a bushing of hard maple. This bushing is driven into the hole in the plate with its grain transverse to the axis of the hole. When the holes are bored, they are made slightly smaller than the pins, which are driven in to an exceedingly tight fit. Now, by studying the sectional view of this device, shown in the accompanying drawing, it wil be seen that the pull of the string upon the tuning pin is applied at a point, less than the diameter of the pin distant from the point at which the pin bears on the hardwood bushing in the plate. Consequently, it is impossible for the pin to be bent down, and the hardwood busing being confined in the metal plate cannot crush, but must hold the pin well up to its work.

"The Mathushek Piano Manufacturing Company was the originator of this method of construction. They have used it continuously for a period of thirty-five years, and they consider that the fact that, after the expiration of the patents, this principle was embodied in some of the best known makes of pianos of their competitors, is exceedingly valuable testimony to the value of its construction."