Usually the change goes on slowly and with a constant replacement of the parts thrown off.

In fairness, though, I must point out that, as the bridge in Kashmir usually spans a stream liable at almost any moment to overwhelming floods, it would appear to be a sound idea to build as flimsily as possible, with an eye to economical replacement.

The adjusting screws would be out of reach; the head of the operator would be in an awkward position; and though these two difficulties might be overcome in some degree, a serious risk of an occasional shift of the plate during the frequent replacement of the dark slide would remain.

Whatever might have been thought, when geological time was supposed to be separated from the present era by a clear line, it is certain that a gradual replacement of old forms by new ones is strongly suggestive of some mode of origination which may still be operative.

Any desk-man taking off during the crucial night-shift, made sure to get in a mutual replacement.

The alternative to that is racial replacement and social decay.

On the contrary, it is generally, if not universally, agreed that the succession of life has been the result of a slow and gradual replacement of species by species; and that all appearances of abruptness of change are due to breaks in the series of deposits, or other changes in physical conditions.

To prepare for this ultimate replacement was one of the points to be most steadily borne in mind, however slowly and tentatively the process might be conducted.