Never before, since the social records of the city have been kept, has society, figuratively speaking, taken so big a jump eastward as this season. Two years ago the social centre was placed by The New York Social Register on the east side of Fifth Avenue, between Sixty-second and Sixty-third Streets. This year it is established on the southeast corner of Madison Avenue and Sixty-fourth Street, the site of the Verona, one of the finest apartment houses on the avenue, and which was put up some ten or twelve years ago, when it seemed to many that Madison Avenue was destined to be the choice apartment thoroughfare of the east side.

This prestige, however, has been captured by Park Avenue, and so far as one may predict in this city of startling changes, the distinction is not likely to be carried off by any other quarter of the city in the near future. While there are individual apartment structures in other localities just as well built, just as well managed, and just as high priced as those on Park Avenue, no other single thoroughfare contains so many magnificent houses which in their appointments appeal to the well-to-do families who formerly occupied expensive houses in the best private residential zones.

Park Avenue is not exclusively an apartment house thoroughfare. Certain sections are being devoted more than ever to splendid private dwellings, fully the equal of the best on upper Fifth Avenue. These sections lie within the Lenox Hill blocks from about Sixty-seventh to Seventy-third Streets, two or three blocks north and south of Eighty-sixth Street, and the Carnegie Hill district in the lower Nineties, but whose development is yet to come.

This private-house development of the avenue on high-class lines has been an interesting feature in the new era which has opened for Park Avenue within the last few years. Elaborate as it has been in some respects, as shown by the handsome new residences of Percy R. Pyne on Sixty-seventh Street, Jonathan Bulkeley on Sixty-fourth Street, Geraldyn Redmond on Sixty-ninth Street, now nearing completion; George Blumenthal at Seventieth Street, George S. Brewster at Seventy-first Street, Oakleigh Thorne at Seventy-third Street, and the Pinchot and De Koven residences at Eighty-fifth Street, the private house growth or improvement is but incidental to Park Avenue's distinguishing characteristic, its long chain of sumptuous apartment houses stretching all the way from Thirty-second nearly to Eighty-sixth Street.

These apartment houses have been the more powerful magnet in drawing the social centre away from Fifth Avenue. This, of course, means that scores of persons more or less prominent in the social world of New York have accepted the apartment style of living. Indeed, it is just for this class of tenants that these houses have been built. Many of them have but one tenant on a floor.

The suites are from twelve to eighteen rooms with many baths and servants' quarters separated from the main living section. The conveniences are superior to the old type of private home, and particular attention has been paid to the facilities for entertaining. They spell the last word in convenience and luxury of living, and a list of the apartment house dwellers on the avenue from the big Montana on the block front on the east side between Fifty-second and Fifty-third Streets to Eighty-sixth Street would include a good proportion of the well-known names in The Social Register. The apartment just mentioned is the largest single apartment structure on the avenue, while that on the northeast corner of Seventy-ninth Street is the tallest not only for Park Avenue, but in the city, being seventeen stories. It may be called the most expensive on the avenue, although others have suites which bring in just as much rental. As showing the tendency of old established families on Fifth Avenue to move to the new society thoroughfare, it may be interesting to mention that among the tenants of this seventeen-story multi-family house is Dr. W. Seward Webb, who, when he sold his Fifth Avenue house near Fifty-fourth Street to John D. Rockefeller, rented one of the floors in this Park Avenue building for his new family home.

The great width of the avenue it is a 140 foot thoroughfare, including the open garden spaces in the middle protecting the open railway cut is one of the advantages which has contributed to make Park Avenue exceptionally available for high class house. This width, however, was no advantage as long as the steam cars were used on the railroad tracks below the thoroughfare. As soon, however, as electricity was substituted for steam, the new era opened. Since that time the rows of old-fashioned five-story flats with their little stores have been almost entirely eliminated. Remnants of early Park Avenue days however may be seen north of Eighty-sixth Street.

In less than ten years about Twenty-five high class Twelve-story houses have gone up and within the last two years the decision of the New York Central Railroad to close up the open cut south of Fifty-ninth Street and build suitable thoroughfares to the cross streets has made all the blocks below Fifty-ninth Street to the railroad yards at about Fiftieth Street available for high Class improvement similar to the blocks north of Fifty-ninth Street. This development, which is well under way seems destined to continue actively for many years.

Lawrence B. Elliman advances another reason which has doubtless been a contributing factor in the evolution of the avenue.

"Park Avenue," he says, "especially on the west side, enjoys much more sunlight than Fifth Avenue, as the houses on the latter avenue are built, as a rule, so deep and approach so closely the side street houses that the rear gets very little sun, and, of course, the front only gets the late afternoon sun in Winter, whereas the west side of Park Avenue enjoys the morning sun.

"For this reason, and also that north of Fifty-ninth Street, the so-called social element of the city must of necessity go east of Fifth Avenue, and because the social element is every year being forced north of Fifty-ninth Street, it seems only natural that the social centre must before many years be located in the neighborhood of Park Avenue and Seventy-second Street."

Douglas L. Elliman, who has been actively identified with many of the large real estate movements which have brought about the present-day transformation, says that Park Avenue is regarded as better and stronger to-day than it has ever been. Despite the mediocre apartment renting season, Park Avenue added over half a dozen large houses to its list, including two or three adjoining on the side streets, and they all rented readily. In the seventeen-story house at Seventy-ninth Street, erected by Bing & Bing, the seventeen suites were rented early at from $12,000 to $14,000 per year. What will take rank as one of the best on the avenue is now under construction on the north-west corner of Sixty-sixth Street by the Fullerton-Weaver Company. There will be but one apartment on a floor of eighteen rooms and six baths, and the rental will be $12,000.

"Fully 400 to 500 fine apartments have been put on the market this season in and adjacent to Park Avenue," said Douglas L. Elliman. "This, taken into consideration with the rapid annual growth during the last five years, gives some idea of these remarkable east side changes, and will serve to explain the social movement away from Fifth Avenue. The bright feature about this change is its apparent permanency. Most of the expensive leases are taken on five-year terms, and the steady demand for large suites of $5,000 and over has been well sustained. The character and standing of the private house residents who have built their own dwellings or are planning to, in the private residential blocks are all an added proof of the long-contained stability assured for this wide east side thoroughfare."

As an indication of the increasing demand for fine apartments in the Park Avenue area, it may be interesting to note that in addition to the twelve-story house now nearing completion on the northwest corner of Sixty-sixth Street, a building similar in size is under construction on the southeast corner of Seventy-second Street, covering the large plot formerly occupied by the Freundschaft Club, and the southeast corner of Seventy-seventh Street is also to be improved in like manner. Below Fifty-ninth Street two big houses of twelve stories each will soon be started, one to be erected by the Goelet estate on the southwest corner of Fifty-fifth Street, and the other on the large plot one block below, recently purchased by Samuel A. Herzog from W. Emlen Roosevelt. This is the southeast corner of Fifty-fourth Street, 100 by 115 feet. In the sale, which was one of the big Park Avenue transactions of the season, Mr. Roosevelt took in part payment the fine twelve-story apartment lately completed by Mr. Herzog at 68 and 70 East Eighty-sixth Street.

The improvement of these two large corners south of Fifty-ninth Street shows the effect that the Grand Central Railroad improvements are exerting in the beautifying of that part of the avenue immediately north of the Grand Central Station and the railroad yards. It has already been shown in the opening last October of the big Martana, covering the entire block front on the east side between Fifty-second and Fifty-third Streets, the site of the old Steinway piano factory. On the same side are two more high-class houses of recent date, one adjoining the northeast corner of Fifty-third Street and the other on the northeast corner of Fifty-fourth Street.

Improvements are gradually being made in the railroad blocks over the yards below Fiftieth Street, from Madison to Lexington Avenues. The new building of the Y.M.C.A. Railroad Branch on the east side of Park Avenue, from Forty-ninth to Fiftieth Street, is now under construction, and when, in the course of a few years, the property over the tracks is fully improved, there will be established over the old smoky railroad yard a centre of harmonious architectural development which will make the blocks north of the station one of the attractive sections of the city.

The cross-streets from Forty-fifth to Fifty-sixth Street have been built in and restored to public use, and ultimately a bridge over Forty-second Street in conjunction with the over-head street that runs around the main terminal building will make Park Avenue a continuous north and south thoroughfare.

Park Avenue is by no means the boundary line of this strong eastward movement. The blocks between that thoroughfare and Third Avenue are showing some striking changes. Plans were recently filed for an eight-story house covering 100 feet front at 116 to 122 East Sixty-third Street. On the southeast corner of Lexington Avenue and Seventy-second Street an eight-story house is going up, and at 103 East Eighty-sixth Street, just east of Park Avenue, a twelve-story building is under construction, designed for four families to a floor.

In the private house development these side streets have witnessed some radical changes, both in the building of new houses and the alteration of old ones into artistic homes. The old-fashioned high stoops are becoming archaic, and in the Seventies some of the best examples in the city of architectural beauty in the small house are to be found. Several blocks between Lexington and Third Avenues have been attractively renovated in this manner, and the private house demand seems destined to move with greater force toward Third Avenue in the next few years.