For years Hammacher has felt an affinity for sculptures in a natural environment. Now that the extension of the museum is complete, he wants to realize a sculpture garden, following the example of Battersea Park in London, Middelheim in Antwerp and Sonsbeek in Arnhem. He envisages a garden with enough space for 50 to 100 works. The sculpture gallery would then ‘continue into the open air and form the transition between an indoor and an outdoor museum’ as it were. Architect Henry van de Velde and the trustees of the Kröller-Müller Foundation support the plan.

After examining several locations, a piece of land measuring three and a half hectares on the east side of the museum is eventually chosen. This site is bordered by the Pampel farm on one side and the Franse Berg on the other and can be well secured due to the proximity of the museum. The land is owned by the Hoge Veluwe National Park Foundation, which would therefore have to provide it to the museum on perpetual lease. The negotiations, however, are difficult.

Nevertheless, the landscape architect Jan Bijhouwer is commissioned to investigate the possibilities of the site. Bijhouwer, professor at the Agricultural College in Wageningen since 1946, always explicitly responds to the characteristics of the specific landscape in his designs. According to him, there is no location more suitable for placing outdoor sculptures than the Hoge Veluwe.

In the spring of 1954, Hammacher visits a retrospective of the work of Barbara Hepworth at the Whitechapel Art Gallery in London. He is very impressed and refers to her sculptures in an article as ‘violins of the space’. He would like to purchase a sculpture immediately, but in the Advisory Committee, Bremmer disagrees. He does not regard the work of the British artist as an important acquisition for the museum.

In July, Hepworth invites Hammacher to her studio in St. Ives in Cornwall, where he would eventually stay for five days. It is the start of a lifelong friendship, in which they often exchange views about her work and Hammacher’s plans for the sculpture garden. Eventually he receives permission from the Committee to purchase 3 drawings and 2 sculptures. Totem, carved from lignum vitae and Pastorale, which the artist calls her most important work: ‘everybody feels that Pastorale is a summary of 20 years’. Because the marble sculpture seems too fragile for the outdoors, Pastorale is given a place in the sculpture gallery. There it dominates the space to such an extent that Hammacher moves two other sculptures so that it can be shown to full effect.

Van de Velde sets strict requirements for his latest project, the auditorium which must be ‘as ideal as the painting galleries’. Although the completion is planned for 17 October 1953, the space cannot be used until March 1954. In accordance with Helene’s wishes, Hammacher immediately makes it ‘a centre of spiritual life in the field of visual art’. ‘The auditorium now makes it possible to host small conferences, organize international gatherings in the world of the arts.’ From that moment on, the chamber music concerts are held there on Sunday afternoons, ‘whereby museum visitors who happen to be present will also be involved’.

Furthermore, the auditorium is used to give visitors a general introduction to the collection. Thereby, Hammacher overcomes the problem that there is so much interest in guided tours that the museum staff cannot meet the demand and he is often forced to help out himself. The plan is also to show an introductory film about the history of the museum, ‘so that future generations do not completely lose touch with this fascinating history’.

In the 1956 annual report, Hammacher expresses his dissatisfaction with the meagre support of the Advisory Committee for his leadership: ‘too many opportunities are never realized and too many owe their realization mainly to the support of third parties’. With this, he refers to the exhibition De kunst van onze tijd. De collectie van de heer Gustave van Geluwe te Brussel (The art of our time. The collection of Mr Gustave van Geluwe of Brussels), which was shown in the summer as part of the Belgian-Dutch Cultural Agreement. Hammacher was allowed to ‘show a selection of 84 paintings, drawings and sculptures from this sublime private collection’, including sculptures by Rik Wouters, Fritz Wotruba, Henri Laurens and Jacques Lipchitz.

Emboldened by the great success of De kunst van onze tijd, the collection of the Belgian Mr and Mrs Urvater is exhibited in Otterlo in the summer of 1957, which includes work by Max Ernst, Paul Klee and René Magritte, artists that according to Hammacher ‘are barely if at all represented in the Dutch museums and collections’. Perhaps for that reason, Van Max Ernst tot Paul Klee (From Max Ernst to Paul Klee) is a real crowd-puller and for the first time in its history the museum receives a hundred thousand visitors.

After the death of H.P. Bremmer and Frits Eschauzier, the Advisory Committee welcomes three new members: Cees van der Leeuw, co-owner of the Van Nelle factory and affiliated with Architecture Department of the Delft University of Technology, the sculptor Oswald Wenckebach and Jan van Gelder, professor of art history in Utrecht and also a former fellow student of Hammacher.

Hammacher now has a favourable wind at his back. Thanks in part to their support, he acquires Child in the sun by Medardo Rosso. The sculpture is made of plaster covered in a layer of wax, in which the marks of the Italian artist’s hands are clearly visible. ‘Through this addition, the distinctive character of Rosso’s sculpting is shown more clearly in the museum, as the almost palpable play of the soft material […] in this small sculpture is even more apparent as an essential feature of Rosso’s working method.’