| Month | Place | Type | Author | Remark |
| 04-01 | Maassluis | 3 vertical dials | Fer de Vries | Special declination and hourangle lines |
| 04-02 | Utrecht, Pieterskerk | Armillary | Hans de Rijk | |
| 04-03 | Lelystad | Analemmatic sundial | Hendrik Hollander | |
| 04-04 | Leiden | 4 vertical dials | Fer de Vries | Chimney dials |
| 04-05 | Oxford | Vertical glass sundial | Fer de Vries | |
| 04-06 | Heukelum | Vertical sundial | Fer de Vries | |
| 04-07 | Nieuwersluis | Vertical sundial | Fer de Vries | 2 on a corner |
| 04-08 | Tietjerk | Cord and spar sun dial | Fer de Vries | Temporary sundial |
| 04-09 | Gemert | Meridian | Fer de Vries | With equation of time curve |
| 04-10 | Vertical sundials | Fer de Vries | Altitude and en azimuth lines | |
| 04-11 | Jorwerd | Vertical sundials | Fer de Vries | Double dial |
| 04-12 | Longyearbyen Norway |
Horizontal sundial | Fer de Vries | |