| 摘要 |
<p>CALCULATION DEVICE FOR FAMILY PLANNING This invention relates to a calculation device for family planning, particularly for pre-planning the sex of a child. The device has a guide plate with a number of parallel guides arranged one above the other. The guide plate is covered by a cover plate which permits viewing of the guides. A number of slides are provided for insertion into the guides. The sliders are divided into sufficient divisions to accommodate the days of at least two successive months. An additional guide has a reference point and a window in the cover plate at a distance of 15 daily divisions from the reference point in the decreasing direction of the daily sequence. Two marker slides extend transversely over the guides and are slidable on the guide plate and cover plate assembly. The lower marker slide with reference to the daily sequence has two windows separated by two daily divisions and each being the width of one daily division. The upper marker slide has one window of the width of one daily division. Recordal of the menstrual cycle on the device permits prediction of those times in a month when conception is likely to result in a female or alternatively a male child.</p> |
